One water pump can fill half of a certain empty tank in 6 hours. Another pump can fill half of the same tank in 6.5 hours. Working together, how long will it take these two pumps to fill the entire tank?	Pick
A) 6 7/13 B) 1 5/8 C) 3 1/4 D) 6 6/25 E) 3 1/2
One pump can fill a tank in 6 hours and another in 6.5 hours   so the rate at which both can half fill the tank is (1/6+1/6.5) =&gt; 25/78   Thus half of the tank can be filled in 78/25   so for filling the complete tank =&gt; 78/25*2 = 156/25 = 6 6/25   ANSWER:6 6/25
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One water pump can fill half of a certain empty tank in 6 hours. Another pump can fill half of the same tank in 6.5 hours. Working together, how long will it take these two pumps to fill the entire tank?