Question

A certain number of persons can finish a task in 85 days. If there were 15 persons more, it would have taken 25 days less for the task to be completed. How many persons are there in the beginning?

• A. 30
• B. 45
• C. 40
• D. 36

Answer 1

Answer:

D. 36

Solution:

Given:

Time taken to finish task = 85 days

No. of extra men added = 15

Time taken to finish the work with 15 extra men = Initial time - 25 days

= 85 - 25

= 60 days

Formula used:

M₁ × D₁ = M₂ × D₂

Calculation:

Let the initial number of men working = N

∴ N × 85 = (N + 15) × 60

⇒ 85N = 60N + 900

⇒ 25N = 900

⇒ N = 900/25

⇒ N = 36

∴ 36 men were working initially.