Question

If 24 men working at 8 hours per day can do a piece of work in 15 days. In how many days can 20 men working at 9 hours per day do the same work?
A. 14 days
B. 16 days
C. 13 days
D. 17 days

Answer 1

Hint - Try to find how much total work is to be done. To find the total work unit use, work unit= No. of men doing the work $ \times $No. of hours$ \times $No. of days, then find the no. of days. As the total amount of work to be done remains the same.

Complete step-by-step answer:
Given 24 men working 8 hours per day can do a work in 15 days.
So, the total work units $
   = 24 \times 8 \times 15 \\
   = 2880 \\
 $
So, 24 men working at 8 hours per day can do 2880 units of work in 15 days.
Therefore, No. of days required by 20 men, working at 9 hours per day $
   = \dfrac{{2880}}{{20 \times 9}} \\
   = 16 \\
 $
So, 20 men working at 9 hours per day do the same work in 16 days.
Hence, the correct option is Option B. 16 days.

Note: Whenever such type of question appears then first try to find out the total amount of work units, here 24 men working at 8 hours per day can do the work in 15 days, so using this information we can find out the amount of work $ = 24 \times 8 \times 15 = 2880$. Then find the no. of days needed for 20 men working 9 hours a day.