A tank is fitted with two taps A and B. A can fill the tank completely in 45 minutes and B can empty the full tank in 1 hour. If both the taps are opened alternatively for 1 minute, then in how much time the empty tank will be filled completely ?

Explanation

LCM OF 45 and 60 is 180.

let the capacity of tank be 180 liters.

rate of filling of A is 4 litres per minute and B takes out water at the rate of 3 liters per minute.

so if both taps are opened alternatively for 1 minute tehn in 2 minutes 1 liter of tank will be filled.

then 176 liters will be filled in 176 x 2=352 minutes. after the 352th minute tap A will open and fill the tank completely so tank will be completely filled in 353 minutes= 5 hours and 53 minutes.