mohsinalinaqvi wrote:Q. There is a leak in the bottom of the tank. This leak can empty a full tank in 8 Hrs. When the tank is full, a tap is opened into the tank which intakes water at a rate of 6 LpHr and the tank is now emptied in 12 Hrs. What is the capacity of the Tank?
a) 169L
b) 144L
c) 132L
d) 120L

We can PLUG IN THE ANSWERS, which represent the capacity of the tank.
The correct answer choice is almost certainly a multiple of 8 hours and 12 hours, the two given times.
Of the four options, only B and D are divisible by both 8 and 12.
When the correct answer choice is plugged in, the time for the leak and the intake together to empty the tank will be 12 hours.

Answer choice B: 144
Since the leak can empty the tank in 8 hours, the leak's rate = w/t = 144/8 = 18 liters per hour.
Since the leak empties the tank at a rate of 18 liters per hour, while the intake pumps in water at a rate of 6 liters per hour, the combined rate for the leak and the intake = 18-6 = 12 liters per hour.
Time for the leak and the intake together to empty the tank = w/r = 144/12 = 12 hours.
Success!

The correct answer is B.