SOLUTION: if 3 water pumps can empty a water tank in 80 minutes, it will take 4 pumps ? minutes to empty the same tank.

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Question 811549: if 3 water pumps can empty a water tank in 80 minutes, it will take 4 pumps ? minutes to empty the same tank.
Found 2 solutions by richwmiller, josgarithmetic:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
3^80=
240 work minutes
240/4=60 minutes for four pumps



Answer by josgarithmetic(39628) About Me  (Show Source):
You can put this solution on YOUR website!
If 80 minutes for 3 pumps, then 3 times longer for just 1 pump.
One pump empties the water tank in 3%2A80=240 minutes.

FOUR pumps go at the rate of 1%2F240%2B1%2F240%2B1%2F240%2B1%2F240=4%281%2F240%29 tanks per minute. This is 60 minutes for four pumps.