Question

3 pumps,working 8 hours a day,can empty a tank in 2 days. how many hours a day 4 pumps works to empty the tank in 1 day?

Answer 1

3 pumps work for 8 hours everday and complete the work in 2 days
1 pump in 1 hr can finish $\frac{1}{48}th$ piece of work
so 4 pumps in one day can finish the work in x hours
$\frac{1}{4x}= \frac{1}{48}=$ 1 pump in 1 hr can finish
$x= \frac{48}{4}=12$
So 4 pumps in 12 hours can finsh the work