Pump A can fill a tank of water in 5 hours. Pump B can fill the same tank in 8 hours. How long does it take the two pumps working together to fill the tank? (round your answer to the nearest minute).

We know that in an hour pump A can fill one-fifth of a tank and pump B can fill one-eighth of the same tank. So we can find out how much both pumps can fill in an hour, while working together by using the equation: 1/5 + 1/8 = 13 / 40 of a tank. Now that we know the rate, 13/40, we can find the time it takes to fill them: (13/40) t = 1 t = 40 / 13 = 39/13 + 1/13 hours = 3 hours and (1/13)*60 minutes = 3 hours 5 minutes (rounded to the nearest minute)

Asked by Tom Tennant · Last updated 5 years ago · 1.8K views · SOURCE