Two pipes function simultaneously, a tank filled in 12 hours. One pipe fill the tank 10 hours faster than the other. How many hours does the faster pipe alone take to fill the tank?

Correct Answer: 20 hrs

Always try to solve these question by options to save time.

total time taken by both pipe

=(x)×(x+10)/(x+10)+x

Now take out one option and put it in place of ‘x’

x = 20 (from option (b))

(20)×(20+10)/(20+10)+(20)=20×30/50=12hrs

It matches with question figure. Total time matches. So, the answer is 20 hrs