CELE Engineering Mathematics — Engineering EconomyExam Answer Templates
Exam-style answer templates for Engineering Economy — how to answer CELE Engineering Mathematics questions when Professional Regulation Commission (PRC) — Board of Civil Engineering asks about this chapter. Use these as your mental checklist on exam day.
Exam context
Professional Regulation Commission (PRC) — Board of Civil Engineering runs the Civil Engineer Licensure Examination on May and November 2026. Its Engineering Mathematics section sits under a "Core" weighting, and Engineering Economy is the 10th chapter in the 10-chapter CELE Engineering Mathematics rotation. The CELE passing mark is 70% weighted average, no sub-test below 50%, and the most recent 2026 paper drew about a meaningful share of questions from Engineering Mathematics.
Engineering Economy - Exam Answer Templates
In the PRC Civil Engineer Licensure Examination, Engineering Economy problems are typically straightforward in concept but punishing in execution — a single arithmetic error or wrong formula selection can cost you all partial marks. Proper answer writing is not merely academic etiquette; it is a scoring strategy. Examiners follow a marking scheme that awards marks for (1) correct formula identification, (2) proper substitution with units, (3) intermediate values, and (4) the final boxed answer. A candidate who writes 'F = P(1+i)^n' before substituting will earn the formula mark even if arithmetic is wrong later. This collection of model answer templates shows you the exact format — from Given/Required/Solution/Answer structure to how to present depreciation schedules — that maximizes your score on every Engineering Economy item in the CE Board Exam.
Templates
Define the 'time value of money' as it applies in Engineering Economy.
Marks
1
Topic
Time Value of Money
Difficulty
easy
Template Id
T1
Examiner Tip
Examiners look for TWO ideas in one sentence: (1) present is worth more and (2) because it can earn interest. Both must appear to earn the mark.
Model Answer
The time value of money is the principle that a sum of money available today is worth more than the same sum available in the future, because money available today can earn interest over time.
Question Type
very_short_answer
Answer Structure
- One concise sentence: state that present money is worth more than future money due to its earning capacity [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct statement that money today is worth more than the same amount in the future AND reason is the earning potential (interest)
Common Mark Deductions
- Vague answer such as 'money has value' without mentioning time or interest
- Confusing time value with inflation without mentioning interest earning
Key Phrases To Include
- worth more today
- earn interest
- earning capacity
- future equivalent
State the formula for effective annual interest rate given a nominal rate r compounded m times per year.
Marks
1
Topic
Nominal vs Effective Interest Rate
Difficulty
easy
Template Id
T2
Examiner Tip
The '− 1' is the most commonly dropped part. Write the full formula on one line and underline or circle the '− 1' to remind yourself it must be there.
Model Answer
i_eff = (1 + r/m)^m − 1 where r = nominal annual rate, m = number of compounding periods per year.
Question Type
very_short_answer
Answer Structure
- Write the formula: i_eff = (1 + r/m)^m − 1 [1 mark]
- Define variables (optional but good practice at 1-mark level)
Scoring Breakdown
Marks
1
Criteria
Correct formula with all three components: (1 + r/m) raised to m, minus 1
Common Mark Deductions
- Writing (1 + r)^m instead of (1 + r/m)^m — dividing by m is essential
- Forgetting the '− 1' at the end
- Using i_eff = r/m (this gives only the per-period rate, not the effective annual rate)
Key Phrases To Include
- i_eff
- (1 + r/m)^m
- minus 1
- nominal rate
- compounding periods
Differentiate simple interest from compound interest. Give the formula for each.
Marks
2
Topic
Simple and Compound Interest
Difficulty
easy
Template Id
T3
Examiner Tip
Write the keyword 'principal only' for simple interest and 'interest on interest' for compound interest — these phrases signal conceptual understanding and are specifically rewarded.
Model Answer
Simple interest is computed only on the original principal, so the interest earned each period is constant. Formula: F = P(1 + in) Compound interest is computed on the accumulated balance (principal plus previously earned interest), so interest earns interest each period. Formula: F = P(1 + i)^n where P = present worth, i = interest rate per period, n = number of periods, F = future worth.
Question Type
short_answer
Answer Structure
- Define simple interest and state its formula: F = P(1 + in) [1 mark]
- Define compound interest and state its formula: F = P(1+i)^n [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct definition and formula for simple interest
Marks
1
Criteria
Correct definition and formula for compound interest
Common Mark Deductions
- Writing F = P + Pin (equivalent but missing the factored form examiners prefer)
- Using 'n' as years without clarifying it is periods (loses precision)
- Swapping the formulas between simple and compound
Key Phrases To Include
- principal only
- F = P(1 + in)
- accumulated balance
- interest on interest
- F = P(1+i)^n
A sum of ₱50,000 is invested today at 12% compounded annually. What is its future worth at the end of 8 years?
Marks
2
Topic
Compound Interest
Difficulty
easy
Template Id
T4
Examiner Tip
Write (1.12)^8 = 2.4760 explicitly before multiplying. This shows you computed the compound factor and earns the substitution mark even if your final multiplication is slightly off.
Model Answer
Given: P = ₱50,000 i = 12% per year = 0.12 n = 8 years Required: Future worth F Solution: F = P(1 + i)^n F = 50,000(1 + 0.12)^8 F = 50,000(1.12)^8 F = 50,000 × 2.47596 F = ₱123,798 Answer: The future worth is ₱123,798.
Question Type
numerical
Answer Structure
- Given block — list P, i, n with units [0.5 mark]
- Write correct formula: F = P(1+i)^n [0.5 mark]
- Correct substitution and computation of (1.12)^8 [0.5 mark]
- Correct final answer with peso sign [0.5 mark]
Scoring Breakdown
Marks
1
Criteria
Correct formula and substitution of given values
Marks
1
Criteria
Correct arithmetic leading to F = ₱123,798 (accept ₱123,795–₱123,800 range for rounding)
Common Mark Deductions
- Using simple interest formula F = P(1+in) instead of compound — most common error
- Not converting percentage: using i = 12 instead of i = 0.12
- Omitting the peso sign in the final answer
Key Phrases To Include
- F = P(1+i)^n
- (1.12)^8 = 2.4760
- ₱123,798
Find the effective annual interest rate corresponding to a nominal rate of 18% compounded monthly.
Marks
2
Topic
Nominal vs Effective Interest Rate
Difficulty
medium
Template Id
T5
Examiner Tip
Always write the intermediate step r/m = 0.18/12 = 0.015. This step alone earns a mark and prevents you from using the wrong per-period rate.
Model Answer
Given: Nominal rate r = 18% per year = 0.18 Compounding frequency m = 12 (monthly) Required: Effective annual rate i_eff Solution: i_eff = (1 + r/m)^m − 1 i_eff = (1 + 0.18/12)^12 − 1 i_eff = (1 + 0.015)^12 − 1 i_eff = (1.015)^12 − 1 i_eff = 1.19562 − 1 i_eff = 0.19562 Answer: The effective annual interest rate is 19.56%.
Question Type
numerical
Answer Structure
- Given: r = 0.18, m = 12 [0.5 mark]
- Correct formula: i_eff = (1 + r/m)^m − 1 [0.5 mark]
- Substitution: (1 + 0.015)^12 [0.5 mark]
- Final answer: 19.56% [0.5 mark]
Scoring Breakdown
Marks
1
Criteria
Correct formula written and correct per-period rate identified (0.015 or 1.5%)
Marks
1
Criteria
Correct effective rate computed as 19.56% (accept 19.56–19.57%)
Common Mark Deductions
- Reporting i_eff = 1.5% (the monthly rate, not the effective annual rate)
- Writing (1 + 0.18)^12 without dividing by m
- Forgetting to subtract 1 at the end
- Leaving the answer as a decimal (0.1956) without converting to percentage
Key Phrases To Include
- i_eff = (1 + r/m)^m − 1
- r/m = 0.015
- m = 12
- 19.56%
Find the present worth of ₱50,000 due in 8 years at 12% compounded annually.
Marks
3
Topic
Present Worth — Compound Interest
Difficulty
easy
Template Id
T6
Examiner Tip
Write both forms: P = F(1+i)^(−n) and P = F/(1+i)^n — this demonstrates full understanding and often earns the formula mark twice in partial-credit schemes.
Model Answer
Given: F = ₱50,000 i = 12% per year = 0.12 n = 8 years Required: Present worth P Solution: Using the present worth formula: P = F(1 + i)^(−n) P = 50,000(1 + 0.12)^(−8) P = 50,000(1.12)^(−8) Compute (1.12)^8 = 2.47596 Therefore (1.12)^(−8) = 1/2.47596 = 0.40388 P = 50,000 × 0.40388 P = ₱20,194 Answer: The present worth is ₱20,194. Verification (optional): F = 20,194(1.12)^8 = 20,194 × 2.47596 ≈ ₱50,000 ✓
Question Type
numerical
Answer Structure
- Given block: F, i, n correctly identified [0.5 mark]
- Correct formula stated: P = F(1+i)^(−n) [1 mark]
- Correct compound factor computed: (1.12)^(−8) = 0.40388 [0.5 mark]
- Correct multiplication and boxed final answer with unit [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct formula P = F(1+i)^(−n) or equivalently P = F/(1+i)^n
Marks
1
Criteria
Correct evaluation of (1.12)^(−8) = 0.40388 or (1.12)^8 = 2.47596
Marks
1
Criteria
Correct final answer ₱20,194 (accept ₱20,190–₱20,200 range)
Common Mark Deductions
- Using F = P(1+i)^n but forgetting to isolate P — solving for F instead
- Confusing the present-worth factor with the compound-amount factor
- Arithmetic error in computing (1.12)^8 — use logarithms or sequential multiplication
Key Phrases To Include
- P = F(1+i)^(−n)
- present worth factor
- (1.12)^8 = 2.47596
- ₱20,194
Annual end-of-year deposits of ₱2,500 are made into an account paying 8% compounded annually for 6 years. Find (a) the future worth and (b) the present worth of this annuity.
Marks
3
Topic
Annuities — Future Worth and Present Worth
Difficulty
medium
Template Id
T7
Examiner Tip
Note that P = F(1+i)^(−n) is a useful cross-check: P = 18,340 × (1.08)^(−6) = 18,340/1.58687 ≈ ₱11,557. Writing this verification line earns goodwill from examiners and confirms your answer.
Model Answer
Given: A = ₱2,500 per year (end-of-year, ordinary annuity) i = 8% per year = 0.08 n = 6 years Required: (a) Future worth F; (b) Present worth P Solution: (a) Future Worth: F = A × [(1+i)^n − 1] / i F = 2,500 × [(1.08)^6 − 1] / 0.08 (1.08)^6 = 1.58687 (1.08)^6 − 1 = 0.58687 0.58687 / 0.08 = 7.3359 ← Future Worth Factor (F/A) F = 2,500 × 7.3359 F = ₱18,340 (b) Present Worth: P = A × [(1+i)^n − 1] / [i(1+i)^n] P = 2,500 × [0.58687] / [0.08 × 1.58687] P = 2,500 × 0.58687 / 0.12695 P = 2,500 × 4.6229 P = ₱11,557 Answer: (a) F = ₱18,340 (b) P = ₱11,557
Question Type
numerical
Answer Structure
- Given block with A, i, n [0.5 mark]
- Correct future-worth annuity formula and computation [1 mark]
- Correct present-worth annuity formula and computation [1 mark]
- Both answers correctly boxed with units [0.5 mark]
Scoring Breakdown
Marks
1
Criteria
Correct future-worth formula F = A[(1+i)^n−1]/i and correct F = ₱18,340
Marks
1
Criteria
Correct present-worth formula P = A[(1+i)^n−1]/[i(1+i)^n] and correct P = ₱11,557
Marks
1
Criteria
Correct identification of ordinary annuity (end-of-period), correct intermediate factor (1.08)^6, proper workings shown
Common Mark Deductions
- Using F = A(1+i)^n instead of the annuity series formula — treating it as a single lump sum
- Forgetting the (1+i)^n denominator in the present-worth formula
- Applying annuity-due (beginning-of-period) adjustment when not required
- Using n = 5 instead of n = 6 by miscounting periods
Key Phrases To Include
- ordinary annuity
- end-of-period
- F = A[(1+i)^n−1]/i
- P = A[(1+i)^n−1]/[i(1+i)^n]
- (1.08)^6 = 1.58687
A scholarship fund is to provide ₱15,000 per year indefinitely. If the fund earns 10% per year, how much must be deposited today to establish the fund?
Marks
2
Topic
Perpetuity
Difficulty
easy
Template Id
T8
Examiner Tip
The word 'indefinitely,' 'forever,' or 'in perpetuity' in a problem is your trigger to use P = A/i. Mention the word 'perpetuity' in your answer — it signals to the examiner that you recognized the problem type correctly.
Model Answer
Given: A = ₱15,000 per year (perpetual/infinite series) i = 10% per year = 0.10 Required: Present worth P of a perpetuity Solution: For a perpetuity (infinite annuity): P = A / i P = 15,000 / 0.10 P = ₱150,000 Answer: A deposit of ₱150,000 must be made today to fund the scholarship indefinitely.
Question Type
numerical
Answer Structure
- Identify as a perpetuity (infinite series) [0.5 mark]
- State formula P = A/i [0.5 mark]
- Correct substitution and answer [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct identification of perpetuity and use of formula P = A/i
Marks
1
Criteria
Correct answer ₱150,000 with proper units
Common Mark Deductions
- Using the finite annuity formula with a very large n instead of P = A/i
- Dividing by 10 instead of 0.10 — giving ₱1,500 (100× error)
- Not recognizing 'indefinitely' as the keyword for perpetuity
Key Phrases To Include
- perpetuity
- infinite series
- P = A/i
- ₱150,000
A machine costs ₱200,000, has a salvage value of ₱20,000, and a useful life of 9 years. Using the straight-line method, find: (a) the annual depreciation charge and (b) the book value at the end of year 4.
Marks
3
Topic
Straight-Line Depreciation
Difficulty
easy
Template Id
T9
Examiner Tip
After computing d, verify: d × n + S = C → 20,000 × 9 + 20,000 = 180,000 + 20,000 = 200,000 ✓. This is a fast, one-line verification that proves your depreciation is correct — write it explicitly.
Model Answer
Given: First cost C = ₱200,000 Salvage value S = ₱20,000 Useful life n = 9 years Required: (a) Annual depreciation d; (b) Book value BV₄ Solution: (a) Straight-line annual depreciation: d = (C − S) / n d = (200,000 − 20,000) / 9 d = 180,000 / 9 d = ₱20,000 per year (b) Book value at end of year 4: BV₄ = C − (d × t) BV₄ = 200,000 − (20,000 × 4) BV₄ = 200,000 − 80,000 BV₄ = ₱120,000 Answer: (a) Annual depreciation = ₱20,000/year (b) Book value after 4 years = ₱120,000
Question Type
numerical
Answer Structure
- Given block: C, S, n [0.5 mark]
- Correct SL formula and annual depreciation d = ₱20,000 [1 mark]
- Correct book value formula BV_t = C − dt and BV₄ = ₱120,000 [1 mark]
- Correct units and boxed answers [0.5 mark]
Scoring Breakdown
Marks
1
Criteria
Correct formula d = (C−S)/n and correct annual depreciation of ₱20,000
Marks
1
Criteria
Correct book value formula BV_t = C − dt and BV₄ = ₱120,000
Marks
1
Criteria
Proper presentation of Given/Required/Solution blocks with units throughout
Common Mark Deductions
- Using C alone without subtracting salvage S: d = 200,000/9 — the most common SL error
- Using BV₄ = C − 4d correctly but with wrong d because of previous error (error carried forward — examiner may still award the BV mark if method is correct)
- Confusing the book value at END of year 4 with the beginning of year 4 (off by one period)
Key Phrases To Include
- d = (C − S)/n
- straight-line method
- BV_t = C − dt
- ₱20,000 per year
- ₱120,000
Using the Sum-of-Years-Digits (SYD) method, find the depreciation charge in year 1 and year 2 for equipment costing ₱250,000 with a ₱25,000 salvage value and an 8-year useful life.
Marks
3
Topic
Sum-of-Years-Digits Depreciation
Difficulty
medium
Template Id
T10
Examiner Tip
Note that SYD accelerates depreciation — year 1 always has the LARGEST charge. As a quick check, the year-1 SYD fraction must be the largest (8/36 here). If your year-1 fraction is smaller than year-2's, you have the formula inverted.
Model Answer
Given: C = ₱250,000 S = ₱25,000 n = 8 years Depreciable amount = C − S = 250,000 − 25,000 = ₱225,000 Required: SYD depreciation for year 1 (d₁) and year 2 (d₂) Solution: Sum of years digits: SYD = n(n+1)/2 = 8(9)/2 = 36 SYD depreciation formula: dₜ = [(n − t + 1)/SYD] × (C − S) Year 1 (t = 1): d₁ = [(8 − 1 + 1)/36] × 225,000 d₁ = [8/36] × 225,000 d₁ = 0.22222 × 225,000 d₁ = ₱50,000 Year 2 (t = 2): d₂ = [(8 − 2 + 1)/36] × 225,000 d₂ = [7/36] × 225,000 d₂ = 0.19444 × 225,000 d₂ = ₱43,750 Answer: Year 1 depreciation = ₱50,000 Year 2 depreciation = ₱43,750
Question Type
numerical
Answer Structure
- Compute depreciable amount C − S = ₱225,000 [0.5 mark]
- Compute SYD = n(n+1)/2 = 36 [0.5 mark]
- Apply dₜ = [(n−t+1)/SYD] × (C−S) for year 1: ₱50,000 [1 mark]
- Apply formula for year 2: ₱43,750 [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct SYD = 36 computed using n(n+1)/2
Marks
1
Criteria
Correct year-1 depreciation: d₁ = (8/36) × 225,000 = ₱50,000
Marks
1
Criteria
Correct year-2 depreciation: d₂ = (7/36) × 225,000 = ₱43,750
Common Mark Deductions
- Using t from the END of life rather than from the beginning: using (t/SYD) instead of [(n−t+1)/SYD]
- Forgetting to subtract salvage: using C instead of (C−S) = 225,000
- Computing SYD as 1+2+...+8 = 36 correctly but then reversing the fraction direction
Key Phrases To Include
- SYD = n(n+1)/2
- dₜ = [(n−t+1)/SYD] × (C−S)
- SYD = 36
- ₱50,000
- ₱43,750
- accelerated depreciation
Monthly deposits of ₱2,000 are made for 3 years into an account paying 6% compounded monthly. Find the future worth at the end of 3 years.
Marks
3
Topic
Annuities — Period Conversion
Difficulty
medium
Template Id
T11
Examiner Tip
Period consistency is the single most tested concept in board-exam annuity problems. Write the conversion step explicitly: 'Convert to monthly: i = 6%/12 = 0.5%; n = 3 × 12 = 36.' This earns a mark even before you touch the formula.
Model Answer
Given: A = ₱2,000 per month Nominal rate r = 6% per year compounded monthly Per-period rate i = 6%/12 = 0.5% per month = 0.005 n = 3 years × 12 months/year = 36 periods Required: Future worth F Solution: F = A × [(1+i)^n − 1] / i F = 2,000 × [(1.005)^36 − 1] / 0.005 Compute (1.005)^36: (1.005)^36 = 1.19668 (1.005)^36 − 1 = 0.19668 0.19668 / 0.005 = 39.336 ← Series compound-amount factor F = 2,000 × 39.336 F = ₱78,672 Answer: The future worth of the monthly deposits is ₱78,672.
Question Type
numerical
Answer Structure
- Convert to per-period rate: i = 0.5%/month = 0.005 [0.5 mark]
- Convert to total periods: n = 36 [0.5 mark]
- State and apply correct annuity formula [1 mark]
- Correct computation and final answer [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct per-period conversions: i = 0.005, n = 36
Marks
1
Criteria
Correct annuity formula F = A[(1+i)^n−1]/i with correct factor
Marks
1
Criteria
Correct final answer F = ₱78,672 (accept ₱78,650–₱78,700)
Common Mark Deductions
- Using i = 6% annual and n = 3 years without converting to monthly — most common and costliest error
- Using n = 3 (years) with i = 0.5% (monthly) — mixed periods
- Using the present-worth formula instead of future-worth formula
Key Phrases To Include
- i = 6%/12 = 0.5% per month
- n = 36 periods
- F = A[(1+i)^n−1]/i
- (1.005)^36 = 1.19668
- ₱78,672
Two machines are being compared. Machine A costs ₱180,000 with annual operating cost of ₱25,000 and a 6-year life with no salvage. Machine B costs ₱120,000 with annual operating cost of ₱35,000 and a 4-year life with no salvage. Using Present Worth analysis at 10% per year, which machine is more economical? Assume repeatability (LCM basis).
Marks
5
Topic
Economic Comparison — Present Worth Method
Difficulty
hard
Template Id
T12
Examiner Tip
Always state the LCM in the first line of your solution. Board examiners immediately check whether you recognized the need for a common study period. Draw a simple cash-flow timeline below your Given block — mark the capital outlays with downward arrows and the AOC with downward arrows. This visual earns no extra mark but prevents you from missing a repeat purchase.
Model Answer
Given: Machine A: P_A = ₱180,000; AOC_A = ₱25,000/yr; life = 6 years; S = 0 Machine B: P_B = ₱120,000; AOC_B = ₱35,000/yr; life = 4 years; S = 0 i = 10% per year Required: Compare total present worth over LCM period; recommend the better machine. Solution Step 1 — Determine LCM study period: LCM(6, 4) = 12 years Machine A: 2 cycles (purchases at year 0 and year 6) Machine B: 3 cycles (purchases at year 0, year 4, year 8) Solution Step 2 — Present Worth of Machine A over 12 years: PW_A = 180,000 + 180,000(P/F, 10%, 6) + 25,000(P/A, 10%, 12) (P/F, 10%, 6) = (1.10)^(−6) = 0.56447 (P/A, 10%, 12) = [(1.10)^12 − 1] / [0.10 × (1.10)^12] = [3.13843 − 1] / [0.10 × 3.13843] = 2.13843 / 0.31384 = 6.8137 PW_A = 180,000 + 180,000(0.56447) + 25,000(6.8137) PW_A = 180,000 + 101,605 + 170,343 PW_A = ₱451,948 Solution Step 3 — Present Worth of Machine B over 12 years: PW_B = 120,000 + 120,000(P/F,10%,4) + 120,000(P/F,10%,8) + 35,000(P/A,10%,12) (P/F, 10%, 4) = (1.10)^(−4) = 0.68301 (P/F, 10%, 8) = (1.10)^(−8) = 0.46651 PW_B = 120,000 + 120,000(0.68301) + 120,000(0.46651) + 35,000(6.8137) PW_B = 120,000 + 81,961 + 55,981 + 238,480 PW_B = ₱496,422 Solution Step 4 — Decision: PW_A = ₱451,948 < PW_B = ₱496,422 Answer: Machine A is more economical because it has the lower total present worth of costs (₱451,948 vs ₱496,422) over the 12-year LCM study period.
Question Type
numerical
Answer Structure
- Identify LCM study period = 12 years [0.5 mark]
- Identify repeat purchase years for each machine [0.5 mark]
- Compute (P/F) and (P/A) factors correctly [1 mark]
- Correct PW_A = ₱451,948 [1 mark]
- Correct PW_B = ₱496,422 [1 mark]
- Correct decision statement with comparison [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct LCM = 12 years and correct repeat-purchase years identified for both machines
Marks
1
Criteria
Correct (P/F) and (P/A) factors at 10% computed or cited (allow ±0.001)
Marks
1
Criteria
Correct total PW_A = ₱451,948 (accept ±₱500)
Marks
1
Criteria
Correct total PW_B = ₱496,422 (accept ±₱500)
Marks
1
Criteria
Correct decision: Machine A, with explicit comparison statement
Common Mark Deductions
- Comparing over different time horizons (6 years vs 4 years) without LCM — invalid comparison
- Forgetting the repeat capital cost at year 6 for Machine A or years 4 and 8 for Machine B
- Adding the annual operating costs as simple sums instead of discounting using (P/A)
- Selecting the machine with lower first cost (₱120,000) without completing the present worth analysis
- No decision statement at the end — a solution without a conclusion loses the decision mark
Key Phrases To Include
- LCM study period
- repeatability assumption
- LCM(6,4) = 12 years
- PW_A < PW_B
- select Machine A
- (P/F, i, n)
- (P/A, i, n)
A project has benefits with a present worth of ₱800,000 and costs with a present worth of ₱550,000. Calculate the benefit-cost ratio and determine whether the project is economically justified.
Marks
2
Topic
Benefit-Cost Analysis
Difficulty
easy
Template Id
T13
Examiner Tip
Always end with an explicit decision: 'Since B/C = ___ > 1.0, the project IS justified' or '< 1.0, the project is NOT justified.' The comparison to 1.0 is the decision criterion and must appear in your answer.
Model Answer
Given: PW of Benefits = ₱800,000 PW of Costs = ₱550,000 Required: Benefit-cost ratio (B/C) and justification decision Solution: B/C = PW of Benefits / PW of Costs B/C = 800,000 / 550,000 B/C = 1.455 Decision: Since B/C = 1.455 > 1.0, the project is economically justified — benefits exceed costs. Answer: B/C ratio = 1.455; the project is economically justified.
Question Type
numerical
Answer Structure
- State formula: B/C = PW Benefits / PW Costs [0.5 mark]
- Compute B/C = 1.455 [0.5 mark]
- Decision: B/C > 1 → justified [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct B/C formula and computation: B/C = 800,000/550,000 = 1.455
Marks
1
Criteria
Correct decision statement: B/C > 1 therefore project is justified
Common Mark Deductions
- Inverting the ratio: C/B instead of B/C
- Stating B/C > 1 is acceptable without identifying the computed value
- Failing to give a clear decision statement
Key Phrases To Include
- B/C = PW Benefits / PW Costs
- B/C = 1.455
- B/C > 1
- economically justified
Two production methods have the following costs. Method X: fixed cost ₱80,000/yr, variable cost ₱12/unit. Method Y: fixed cost ₱120,000/yr, variable cost ₱8/unit. Find the break-even volume and state which method is preferred above and below that volume.
Marks
3
Topic
Break-Even Analysis
Difficulty
medium
Template Id
T14
Examiner Tip
Always verify by substituting Q back: TC_X = 80,000 + 12(10,000) = ₱200,000 and TC_Y = 120,000 + 8(10,000) = ₱200,000. If they match, your break-even is correct. Write this one line — it demonstrates rigor and is expected at board-exam level.
Model Answer
Given: Method X: FC_X = ₱80,000/yr, VC_X = ₱12/unit Method Y: FC_Y = ₱120,000/yr, VC_Y = ₱8/unit Required: Break-even volume Q_BE; preferred method above and below Q_BE Solution: At break-even, total cost of Method X = total cost of Method Y: TC_X = TC_Y FC_X + VC_X × Q = FC_Y + VC_Y × Q 80,000 + 12Q = 120,000 + 8Q 12Q − 8Q = 120,000 − 80,000 4Q = 40,000 Q = 10,000 units/year Decision: Below Q_BE (Q < 10,000 units): Method X has lower total cost (lower fixed cost dominates) Above Q_BE (Q > 10,000 units): Method Y has lower total cost (lower variable cost dominates) At Q = 10,000 units: both methods have equal cost of: TC = 80,000 + 12(10,000) = ₱200,000 ✓ Answer: Break-even volume = 10,000 units/year. Method X is preferred for volumes below 10,000 units; Method Y is preferred above 10,000 units.
Question Type
numerical
Answer Structure
- Set up cost equations for both methods [0.5 mark]
- Equate TC_X = TC_Y and solve algebraically for Q [1 mark]
- Q_BE = 10,000 units [0.5 mark]
- Correct preference statements above and below Q_BE [1 mark]
Scoring Breakdown
Marks
1
Criteria
Correct setup of TC_X = TC_Y equation with fixed and variable cost terms
Marks
1
Criteria
Correct break-even volume Q = 10,000 units
Marks
1
Criteria
Correct preference decision above and below the break-even point with reasoning
Common Mark Deductions
- Forgetting fixed costs and only equating VC_X × Q = VC_Y × Q
- Computing Q correctly but reversing the preference decisions (saying Y is preferred at low volumes)
- Not verifying the answer by substituting Q back into both cost equations
Key Phrases To Include
- break-even volume
- TC_X = TC_Y
- FC + VC × Q
- 10,000 units
- lower fixed cost
- lower variable cost
An investment of ₱100,000 today is expected to yield ₱30,000 per year for 5 years. Determine whether this investment is acceptable if the minimum attractive rate of return (MARR) is 15% per year, using the Net Present Worth method.
Marks
5
Topic
Net Present Worth — Investment Decision
Difficulty
hard
Template Id
T15
Examiner Tip
A complete 5-mark NPW answer MUST contain: (1) the factor formula, (2) the computed factor value, (3) the NPW calculation, and (4) the decision statement. Missing the decision statement is the most common way a candidate loses the last mark on an otherwise perfect computation.
Model Answer
Given: Initial investment P₀ = ₱100,000 (cost, cash outflow at t = 0) Annual return A = ₱30,000/year (cash inflow at end of each year) n = 5 years MARR = 15% per year = 0.15 Required: Net Present Worth (NPW); accept/reject decision Solution Step 1 — Present Worth of Benefits (inflows): PW_benefits = A × (P/A, 15%, 5) (P/A, 15%, 5) = [(1.15)^5 − 1] / [0.15 × (1.15)^5] (1.15)^5 = 2.01136 (1.15)^5 − 1 = 1.01136 0.15 × 2.01136 = 0.30170 (P/A, 15%, 5) = 1.01136 / 0.30170 = 3.3522 PW_benefits = 30,000 × 3.3522 = ₱100,566 Solution Step 2 — Net Present Worth: NPW = PW_benefits − Initial Investment NPW = 100,566 − 100,000 NPW = ₱+566 Solution Step 3 — Decision: Since NPW = +₱566 > 0, the investment yields a return EXCEEDING the MARR of 15%. Answer: NPW = +₱566 > 0; the investment is ACCEPTABLE. (The project barely exceeds the MARR — the actual IRR is slightly above 15%.) Note: If NPW = 0, the investment earns exactly the MARR. If NPW < 0, reject.
Question Type
numerical
Answer Structure
- Given block with all four values clearly listed [0.5 mark]
- Identify and compute (P/A, 15%, 5) factor [1 mark]
- Compute PW of benefits = ₱100,566 [1 mark]
- Compute NPW = PW_benefits − initial cost [1 mark]
- Correct decision: NPW > 0 → accept [1 mark]
- Brief note on interpretation of NPW sign [0.5 mark]
Scoring Breakdown
Marks
1
Criteria
Correct (P/A, 15%, 5) = 3.3522 computed from formula (accept 3.352–3.353)
Marks
1
Criteria
Correct PW of benefits = 30,000 × 3.3522 = ₱100,566
Marks
1
Criteria
NPW = 100,566 − 100,000 = +₱566
Marks
1
Criteria
Correct accept decision with criterion NPW > 0 stated
Marks
1
Criteria
Proper problem setup showing understanding of NPW = PW(benefits) − PW(costs) structure
Common Mark Deductions
- Simply summing the undiscounted cash flows: 5 × 30,000 = 150,000 − 100,000 = 50,000 — ignoring time value entirely
- Using the wrong factor: (F/A) instead of (P/A) for the annuity present worth
- Computing NPW but not providing a clear accept/reject decision with criterion
- Using i = 15 instead of i = 0.15 in the formula
Key Phrases To Include
- NPW = PW(benefits) − PW(costs)
- MARR
- (P/A, 15%, 5) = 3.3522
- NPW > 0
- acceptable
- exceeds MARR
Mark Wise Strategy
Dos
- Write the formula on a single clear line
- Include variable definitions if space allows
- Use engineering terms exactly as they appear in textbooks
- Underline or bold the key term you are defining
Donts
- Do not write lengthy explanations — you waste time and blur the key point
- Do not leave any 1-mark question blank — a partial attempt can still earn the mark
- Do not write in narrative prose; be direct and formulaic
Marks
1
Strategy
State a precise definition or formula without elaboration. Every word must count. Use exact engineering terminology — 'time value of money,' 'compounding period,' 'perpetuity,' etc.
Expected Length
1–2 lines or one formula
Time Allocation
1–2 minutes
Dos
- Write Given values in a bullet list at the top
- State the formula in symbolic form before substituting numbers
- Show the substitution step explicitly
- Box or underline the final numerical answer with ₱ sign
Donts
- Do not skip directly to the numerical answer — formula mark can be lost
- Do not omit units (₱ for money, % for rates, years for time)
- Do not round intermediate steps — keep at least 4 significant figures
Marks
2
Strategy
Use the two-block structure: (1) State the formula and (2) Substitute and solve. Show one intermediate step. Box your final answer with units.
Expected Length
3–6 lines including Given, formula, and answer
Time Allocation
3–5 minutes
Dos
- Use GRSA structure without exception
- Label intermediate computed values (e.g., (1.08)^6 = 1.58687) explicitly
- For depreciation: present a mini-table showing year, depreciation, book value
- Write a final decision or interpretation statement for comparison problems
Donts
- Do not combine multiple steps into one line — partial marks require visible working
- Do not assume the examiner knows what formula you used — state it
- Do not forget to answer both parts if the question has (a) and (b)
Marks
3
Strategy
Use the full Given–Required–Solution–Answer (GRSA) four-block structure. For multi-part questions, label each part clearly (a, b, c). Show every intermediate step since marks are awarded for process, not just the final answer.
Expected Length
10–15 lines with full GRSA structure
Time Allocation
6–8 minutes
Dos
- Number your solution steps and give each a short descriptive heading
- Draw or describe a cash-flow diagram (timeline) to organize your thinking
- Show all factor computations: (P/A, i, n) = formula = value
- Write an explicit decision statement with the basis for the decision (NPW > 0, lower PW, B/C > 1)
- Leave space between steps for readability — cramped answers are harder to mark
Donts
- Do not rush to the answer — the working is where 3 of the 5 marks live
- Do not compare alternatives without a common study period (LCM or specified period)
- Do not omit the decision or conclusion — this is always worth at least 1 mark
- Do not mix compounding periods (annual rate with monthly periods) without explicit conversion
Marks
5
Strategy
Treat this as a mini-essay with numbered solution steps. Organize into Step 1, Step 2, Step 3, etc. Each step should have a heading (e.g., 'Step 1 — Determine LCM study period'). Show all factor computations, present a cash-flow summary, and end with an explicit decision statement. Partial marks are awarded at every step.
Expected Length
20–30 lines with numbered solution steps
Time Allocation
12–15 minutes
General Answer Writing Tips
- Always write the 'Given–Required–Solution–Answer' (GRSA) four-block structure for any numerical problem worth 2 marks or more; this organizes your work and guarantees partial marks even if your final answer is incorrect.
- State the formula in its general symbolic form FIRST (e.g., F = P(1+i)^n), THEN substitute numerical values; examiners award a separate mark for correct formula identification.
- Match your interest rate period to your compounding period — always convert the nominal rate to a per-period rate before substituting (e.g., 12% compounded monthly → i = 1% per month, not 12%).
- Box or encircle your final numerical answer and always include the peso sign (₱) or the correct unit; an answer without a unit in a money problem is technically incomplete.
- For depreciation problems, present values in a table (Year | Depreciation | Book Value) to earn full marks and make checking easy for both you and the examiner.
- When comparing alternatives using Present Worth or Annual Worth, clearly label each alternative (Alternative A, Alternative B) and state your decision: 'Select Alternative ___ because it has the lower/higher ___.'
- Show at least three significant figures in intermediate calculations and round only the final answer to two decimal places (pesos and centavos) unless told otherwise.
- On effective-rate and nominal-rate conversions, write the conversion formula completely before substituting — never skip directly to the decimal; examiners look for evidence of correct reasoning, not just the correct number.
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