ITPEC IP April 2026 Question 53
In a development project for a system, there is a plan to create 36 programs with the same size. It was first planned to assign only Mr. A who can create six (6) programs per week, but the plan was changed and it was decided to assign two (2) people: Mr. A, and Mr. B who has half the productivity of Mr. A. When the cost per week for Mr. A and Mr. B is 300 thousand yen and 200 thousand yen respectively, how much is the change in the cost as compared to the original plan? Here, Mr. A and Mr. B perform activities in parallel, and the efficiency of Mr. A and Mr. B are always fixed.
Explanation
An increase of 200 thousand yen — adding Mr. B shortens the work, but the extra weekly cost outweighs the weeks saved.
- •Original plan: Mr. A alone takes 36 ÷ 6 = 6 weeks and costs 6 × 300 = 1800 thousand yen
- •Mr. B has half the productivity: 6 ÷ 2 = 3 programs per week, so together they make 9 per week and need 36 ÷ 9 = 4 weeks
- •New plan: 4 × (300 + 200) = 2000 thousand yen
- •Change: 2000 − 1800 = 200 thousand yen more
Answer (c)
Why not others:
- •(a) A decrease of 800 — takes Mr. B as twice as productive as Mr. A: 18 per week, 2 weeks, 2 × 500 = 1000
- •(b) A decrease of 300 — takes Mr. B as productive as Mr. A: 12 per week, 3 weeks, 3 × 500 = 1500
- •(d) An increase of 1,200 — pays both people for the original 6 weeks, 6 × 500 = 3000, forgetting that the work now ends in 4
Key rule: The cost of a staffing change is the new duration, from the combined productivity, times the combined weekly rate; a slower second person shortens the schedule but can still raise the total cost.
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