A type has 3 punctures. The first puncture alone would have made the tyre flat in 14 minutes, the second alone would have done it in 28 minutes, the third alone would have done it in 56 minutes. If air leaks out at a constant rate, how long (in minutes) does it take for all the punctures together to make the tyre flat?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 8.
LCM(14, 28, 56) = 56
The efficiency of first puncture = 56/14 = 4
The efficiency of second puncture = 56/28 = 2
The efficiency of third puncture = 56/56 = 1
Time taken = = = 8 minutes