Pumping alone at their respective constant rates, one inlet pipe fills an empty tank to 1/2 of capacity in 3 hours and a second inlet pipe fills the same empty tank to 2/3 of capacity in 4 hours. How many hours will it take both pipes, pumping simultaneously at their respective constant rates, to fill the empty tank to capacity?	Choose the correct option:
A) 3  B) 3.6  C) 4.2  D) 4.4  E) 5.5
Time taken by First tank Fill 1/2 the tank = 3 hours   i.e. Time taken by First tank to Fill 1 complete the tank = 6 hours   Time taken by Second tank Fill 2/3 the tank = 4 hours   i.e. Time taken by First tank to Fill 1 complete the tank = (3/2)*4= 
<gadget id="calculator">(3/2)*4</gadget>
<output>6</output>
6 hours   in 1 Hour, Both tanks together Fill the tank= (1/6)+(1/6) = 1/3 tank   i.e. Time taken by Both tank to Fill 1 complete the tank = 3 hours   3
<result>A</result>
Pumping alone at their respective constant rates, one inlet pipe fills an empty tank to 1/2 of capacity in 3 hours and a second inlet pipe fills the same empty tank to 2/3 of capacity in 4 hours. How many hours will it take both pipes, pumping simultaneously at their respective constant rates, to fill the empty tank to capacity?