Question

Twenty four men can do a work in 35 days. How many men are required to complete the work in 21 days?
Select one:
a. 42
b. 36
c. 38
d. 40

Answer 1

Answer:

Option (d) 40

Explanation:

∵ 24 men can do a work in = 35 days

∴ Work done by 24 men in 1 day = 1/35

∴ Work done by 1 man in 1 day = $\frac{1}{35\times 24}$

∴ Work done by 1 man in 21 days = $21\times \frac{1}{35\times 24}=\frac{1}{40}$

Let the it takes n no. of men to complete the work in 21 days

Then

$n\times \frac{1}{40}=1$

$\implies n=40$

Hope this helps.

Answer 2

d. 40 men are required to complete the work in 21 days.

Explanation:

From question, 24 men can do a work = 35 days

Thus, work done by 24 men in 1 day = 1/35

The work done by 1 man in 1 day = 1/(35 × 24)

This, the work done by 1 man in 21 days = 21 × 1/(35 × 24) = 0.025

The number of men work in 21 days is:

N × 0.025 = 1

⇒ N = 1/0.025

∴ N = 40 men