A tap can fill a tank in 10 minutes and another can empty it in 6 minutes. If the tank is fill already two-fifths and both the taps are opened together, how long will it take to completely emptied?

Question: A tap can fill a tank in 10 minutes and another can empty it in 6 minutes. If the tank is fill already two-fifths and both the taps are opened together, how long will it take to completely emptied?

Solution:
Given,
the outlet pipe is faster than the inlet pipe

Part to be emptied = 2/5 part

Net part emptied in 1 minute = (1/6 - 1/10) = (5 - 3)/30 = 2/30 = 1/15 part

ATQ,
1/15 part is emptied in 1 minute
∴ 2/5 part is emptied in (15 × 2/5) minute
= 6 minutes