SOLUTION: Pump A can fill a tank of water in 4 hours. Pump B can fill the same tank in 6 hours. Both pumps are started at 8:00 a.m. to fill the same empty tank. An hour later, pump B breaks

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Pump A can fill a tank of water in 4 hours. Pump B can fill the same tank in 6 hours. Both pumps are started at 8:00 a.m. to fill the same empty tank. An hour later, pump B breaks       Log On


   

Question 704592: Pump A can fill a tank of water in 4 hours. Pump B can fill the same tank in 6 hours. Both pumps are started at 8:00 a.m. to fill the same empty tank. An hour later, pump B breaks down and took one hour to repair and was restarted again. When will the tank be full? (round your answer to the nearest minute).
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
Pump A rate = 1/4 tank per hour
Pump B rate = 1/6 tank per hour
Both pumps together rate = 1/4 + 1/6 tank per hour
Time pump A alone = 1 hour
Time pumpts together = t-1 hour
t, unknown time in hours.

Sum of jobs = The Whole Job.
(1/4)*1 amount of the job for A while worked alone
(1/4+1/6)*(t-1) amount of job for both pumps together

%281%2F4%29%2A1%2B%281%2F4%2B1%2F6%29%2A%28t-1%29=1, the whole tank job.
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t=14%2F5=2%264%2F5 hours