Question

PipeA can fill a tank in 5 hours and pipe B in 10 hours both the pipes are opened together and after 2 hours pipe A is closed how much time will be taken by pipe B to fill the remaining tank?

Answer 1

A takes 5hrs and B takes 10 hrs to fill the same tank.

Then B=2A and if A was opened for 2 hours then for B it will be equal to 4 hours

B is also opened for 2 hrs then 4+2=6 hrs

hence ans=10-6=4 hrs

Answer 2

hope it is helpfull

pipeA fill tank in 5 hours and B in 10 hours.
total time=1/5+1/10 = 3/10 .
after 2 hours a is closed=3/10*2 = 3/5 .
remaining 1- 3/5= 2/5
time taken to b to comp. remaining part = 2/5*10 = 4 hours