Taps A and B can fill a tank in 10 hours and 30 hours, respectively. Taps And D cm empty the tank in 20 hours and 25 hours, respectively. When the tank is full, both tops Cam D are opened for 10 hours and then, both taps C and D are closed and tap A is opened How much more time does it take to fill the tank completely
Answers
Step-by-step explanation:
Tap A can fill a tank in 10 hours -> In 1 hour it fills +10% of the tank.
Tap B can fill it in 20 hours -> In 1 hour it fills +5% of the tank.
Tap C can empty the tank in 30 hours -> In 1 hour it fills -) % of the tank.
Each tap is opened, one by one, for exactly one hour and then closed.
Therefore in every 3 hours: 10% + 5% - % = % of the tank gets filled.
The tank is already full. Therefore, we only have i.e. 75% of the tank to fill.
In 18 hours, it fills: % * 6 = 70%
In the 19th hour, Tap A will start filling which will fill +10% in one hour. However, we only need +5% to make it 75%.
So Tap A should fill +5 % in ½ hour i.e. 30 minutes.
Therefore, it will take 18 hours 30 minutes to completely fill the tank, after which it will begin to overflow.