SSC CPO 2022 PYQ — Question 122

The correct answer is Option 2 i.e. $\frac{16}{75}$.

We know that,

Efficiency = Total work done/Number of days

Now, 

12 men or 20 boys can finish the work in 10 days

So, 12 M = 20 B

⇒ M/B = 5/3

Now, 12 men worked for 10 days

Total work done = 12 × 5 × 10 = 600 unit

Now, 4 men and 4 boys will work in 4 days

⇒ [(4 × 5) + (4 × 3)] × 4

⇒ 128

The part of the same work done = 128/600 = $\frac{16}{75}$

Hence, 16/75 of the same work is done by 4 men and 4 boys.