Solve.
-One pump can drain a pool in 12 minutes. When a second pump is also used, the pool only takes 9 minutes to drain. How long would it take the second pump to drain the pool if it were the only pump in use?
A) $105 \mathrm {~min}$
B) $5 \frac { 1 } { 7 } \mathrm {~min}$
C) $\frac { 1 } { 36 }$ min
D) $36 \mathrm {~min}$

Question

Quizplus · Accepted Answer

The first pump drains 1/12 of the pool per minute, and together they drain 1/9 of the pool per minute. Subtracting the rate of the first pump from the combined rate gives the rate of the second pump: 1/9 - 1/12 = 1/36 of the pool per minute. Therefore, it would take the second pump 36 minutes to drain the pool alone.

Solve -One Pump Can Drain a Pool in 12 Minutes 105 min105 \mathrm {~min}105 min

Solve
-One Pump Can Drain a Pool in 12 Minutes $105 \mathrm {~min}$