# A tap can fill a tank in 15 minutes. Another tap can empty it in 20 minutes

A tap can fill a tank in 15 minutes. Another tap can empty it in 20 minutes. Initially the tank is empty, if both the taps start functioning at the same time, when with the tank become full?

A. 1 hour

B. 3 hours

C. 2 hours

D. 4 hours

**Answer: (A) 1 hour **

**Solution:-**

A tap can fill a tank = 15 min

Therefore, A tap can fill a tank in a min = 1/15

Another tap can empty same tank = 20 min

Therefore, Another tap can empty a same tank = 1/20

If both the taps start functioning at the same time,

Then, time taken by both tap to fill tank in a min = 1/15 – 1/20

= (4 – 3)/60

= 1/60

Both tank fill the tank = 60 min.

Hence, the correct answer is option (A) 1 hour.