Apond is being drained by a pump. after 3 hours, the pond is half empty. a second pump is put into operation and together the two pumps finish emptying the pond in half an hour. how long would it take the second pump to drain the pond if it had to do the same job alone?

The first pump empties half the pond in 3 hours, so in 1/6 that time (1/2 hour), it empties (1/6)·(1/2) = 1/12 of the pond.

The second pump empties the other 5/12 of the pond in that half hour, so has a pumping rate of (1/2 h)/(5/12 pond) = (6/5 h)/pond.

The second pump could do the entire job alone in 1 hour and 12 minutes.

it should be a and d. lmk if i'm wrong xd

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