SammyJaggi wrote:Pipe A can fill a pool in 5 days and pipe B can fill the pool in 3 days .if they start working together at same time,how long(in hours) will it take to fill the pool. if pipe B stops working after a DAy??

Pipe A can fill pool in 5 days
In one day Pipe A can fill = 1/5 = 3/15 (multiply by 3 on Nr and Dr)

Similarly,
In one day Pipe B can fill = 1/3 = 5/15 (multiply by 3 on Nr and Dr)

Together in one day they can fill = 3/15 + 5/15 = 8/15 of pool....

Remaining = 1-8/15 = 7/15
Since Pipe B stops working after 1 day, Pipe A has to fill 7/15 of pool alone (awwww....Poor Pipe A)
So Pipe A will take = (7/15)/(3/15) = 7/3 Days

So total no. of days req to fill the pool is = 1 + 7/3 = 10/3 Days

Remember, We have to find no. of hours....not no. of days..(multiply by 24)

So, No. of hours = 80Hrs

SammyJaggi wrote:Pipe A can fill a pool in 5 days and pipe B can fill the pool in 3 days .if they start working together at same time,how long(in hours) will it take to fill the pool. if pipe B stops working after a DAy??

Let the pool = 15 units.

Rate for A = w/t = 15/5 = 3 units per day.
Rate for B = w/t = 15/3 = 5 units per day.
Work produced by A and B in one day = 3+5 = 8 units.
Time for A to fill the remaining 7 units = w/r = 7/3 days = (7/3)(24 hours) = 56 hours.
Total time = one day + 56 hours = 24+56 = 80 hours.