Two taps, A and B, fill a tank in 15/2 minutes and 5 minutes, respectively, while an outlet tap, C, drains 14 litres of water per minute. If the tank is initially full and all three taps are opened, the tank becomes empty in 1 hour. What is the capacity of the tank?
A
60 litres
B
80 litres
C
40 litres
D
20 litres
Correct Option:
C
Explanation
A fills at 1 tank/7.5 = 2/15 tank/min, B at 1/5 tank/min. Together = 1/3 tank/min. C drains 14 L/min. Since a full tank becomes empty in 60 min: 14 − V/3 = V/60. Thus, 14 = 21V/60 = 7V/20, giving V = 40 L.