Question 1108121
A small pump can drain a pool in 4 hours. A large pump could drain the same pool in 3 hours. How long (to the nearest minute) will it take to drain the pool if both pumps are used simultaneously?
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Small drains 1/4 pool/hr
Large drains 1/3 pool/hr
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1/4 + 1/3 = 7/12 pool/hr
Invert
hr/pool = 12/7 hours