Two pipes P and Q can fill a tank in 5 hours and 6 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 options.
A) 4 hours 20 min B) 2 hours 44 min C) 3 hours 50 min D) 3 hours 22 min E) 3 hours 42 min
Explanation:   Part filled by P in 1 hour = 1/5   Part filled by Q in 1 hour = 1/6   Part filled by (P + Q) in 1 hour = ( 1/5 + 1/6) = (11/30)   Time taken to fill the tank is (30/11) = 2 hours 44 min   ANSWER 2 hours 44 min
<result>B</result>
Two pipes P and Q can fill a tank in 5 hours and 6 hours respectively. If both pipes are opened simultaneously, how much time will be taken to fill the tank?