# SOLUTION: a 5 horsepower (hp) pump can empty a pool in 5 hours. a smaller, 2 hp pump empties the same pool in 8 hours. the pumps are used together to begin emptying this pool. after 2 hours,

Algebra ->  Algebra  -> Rate-of-work-word-problems -> SOLUTION: a 5 horsepower (hp) pump can empty a pool in 5 hours. a smaller, 2 hp pump empties the same pool in 8 hours. the pumps are used together to begin emptying this pool. after 2 hours,      Log On

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 Click here to see ALL problems on Rate-of-work-word-problems Question 167649: a 5 horsepower (hp) pump can empty a pool in 5 hours. a smaller, 2 hp pump empties the same pool in 8 hours. the pumps are used together to begin emptying this pool. after 2 hours, the 2 hp pump breaks down. how long will it take the larger pump to finish emptying the pool? --- i get that for the entire time, minus the 2hp pump breaking down, the equation would be 1/5+1/8=1/t, 8t+5t=40, 13t=40, t=40/13=3.08hours... but i do not know how to take into consideration the 2hp pump breaking down. any help would be much appreciated! Answer by stanbon(57424)   (Show Source): You can put this solution on YOUR website!a 5 horsepower (hp) pump can empty a pool in 5 hours. a smaller, 2 hp pump empties the same pool in 8 hours. the pumps are used together to begin emptying this pool. after 2 hours, the 2 hp pump breaks down. how long will it take the larger pump to finish emptying the pool? --------------- 5 hp pump DATA: time = 5 hrs/job ; rate = 1/5 job/hr ---------------------- 2 hp pump DATA: time = 8 hrs/job ; rate = 1/8 job/hr ---------------------- In two hours working together, 2(1/5 + 1/8) = 2(13/40) = 13/20 of the job is done. That leaves 7/20 of the job to be done by the 5 horsepower pump. ------------- Let time for the 5 hp to finish the job be "x" hrs. x(1/5) = 7/20 x = 7/4 hr = 1 3/4 hr. = 1 hr. 45 minutes ============================= Cheers, Stan H.