A certain number of men can do a piece of work in 80 days.

Home » Aptitude » Time and Work » Question

A certain number of men can do a piece of work in 80 days. If there were 10 men less, it could be finished in 20 days more. How many men are there in the starting ?

1. 45
2. 50
3. 40
4. 60

Correct Option: B

Let the original number of men = N
Time taken by N = 80 days
Now, (N - 10) men can finish the work in the (80 + 20) = 100 days
Here, M₁ = N, M₂ = (N - 10), D₁ = 80 and D₂ = 100
According to the formula.
M₁D₁ = M₂D₂
⇒ N x 80 = 100 x (N - 10)
⇒ 8N = 10N - 100
⇒ 10N - 8N = 100
⇒ N = 50