Two pipes P and Q can fill a tank in 4 hours and 5 hours respectively. If both pipes are opened simultaneously, how much time will be taken to fill the tank? Choose the correct choice from the following choices:	A) 4 hours 20 min	B) 5 hours 49 min	C) 3 hours 50 min	D) 3 hours 22 min	E) 2 hours 13 min
2 hours 13 minxplanation:   Part filled by P in 1 hour = 1/4   Part filled by Q in 1 hour = 1/5   Part filled by (P + Q) in 1 hour = ( 1/4 + 1/5) = (9/20)   Time taken to fill the tank is (20/9) = 20/9*60 = 133 mins = 2 hrs 13 mins   ANSW2 hours 13 minR 2 hours 13 min
<result>E</result>
Two pipes P and Q can fill a tank in 4 hours and 5 hours respectively. If both pipes are opened simultaneously, how much time will be taken to fill the tank?