Pipe A fills a swimming pool in 4 hours. Pipe B empties the pool in 6 hours. If pipe A was opened at 5:00 am and Pipe B at 6:00 am, at what time will the pool be full?  Pick:  A) 13:00  B) 14:00  C) 15:00  D) 17:00  E) 16:00
Pipe A fills the pool in 4 hrs.   1 hour's work : 1/4   Pipe B empties the pool in 6 hrs.   1 hour's work : 1/6   Together if they work, 1 hour's work = 1/4 -1/6 = 1/12   Given : Pipe A started at 5:00 a.m and Pipe B at 6:00 a.m   Pool filled after 1 hour by Pipe A : 1/4 or 3/12   After 6:00 a.m   Pool filled after 1 hour with both the pipes on : 1/12   Pool filled after 9 hours with both pipes on : 9/12   Pool filled in 1 hour + Pool filled in 9 hours = 3/12 +9/12= 
<gadget id="calculator">3/12 +9/12</gadget>
<output>1</output>
1   Therefore, it takes 10 hrs to fill the pool   As Pipe A started at 5:00 a.m, pool is full at 15:00 hrs   Answer : 15:00
<result>C</result>
Pipe A fills a swimming pool in 4 hours. Pipe B empties the pool in 6 hours. If pipe A was opened at 5:00 am and Pipe B at 6:00 am, at what time will the pool be full?