Three pipes can fill a tank in 15 hours, 12 hours and 10 hours, respectively. If all the three pipes are opened simultaneously for 3 hours, then what percentage of the tank will remain unfilled?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 25%
LCM of 15, 12, and 10 = 60 ⇒Total capacity = 60 units
Efficiency :
Pipe A = 60 ÷ 15 = 4 units/hour
Pipe B = 60 ÷ 12 = 5 units/hour
Pipe C = 60 ÷ 10 = 6 units/hour
Work done in 3 hours = (4 + 5 + 6) × 3 = 15 × 3 = 45 units
Remaining work = 60 − 45 = 15 units
(15/60) × 100 = 25%