A water tank can be filled in 8 minutes and emptied in 9 minutes. If the drain is accidentally left open when the tank is being filled, how long does it take to fill the tank?
A) $\frac{1}{72}$ minutes

B) 72 minutes

C) $4 \frac{4}{17}$ minutes

D) $\frac{1}{17}$ minutes

Question

A water tank can be filled in 8 minutes and emptied in 9 minutes. If the drain is accidentally left open when the tank is being filled, how long does it take to fill the tank?
A) $\frac{1}{72}$ minutes

B) 72 minutes

C) $4 \frac{4}{17}$ minutes

D) $\frac{1}{17}$ minutes

Quizplus · Accepted Answer

The tank fills at a rate of 1/8 tank per minute and empties at a rate of 1/9 tank per minute. The net fill rate when both are open is 1/8 - 1/9 = 1/72 tank per minute. Therefore, to fill the tank completely, it would take 72 minutes.

A Water Tank Can Be Filled in 8 Minutes and Emptied