A tyre has 3 punctures. The first puncture alone would have made the tyre flat in 9 minutes, the second alone would have done it in 18 minutes, the third alone would have done it in 6 minutes. If the air leaks out at a constant rate, then how long (in minutes) does it take for all the punctures together to make it flat?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 3
Let's the capacity of the tire = LCM of 9, 6, and 18 = 18
Efficiency of the first puncutres = 18/9 = 2
Efficiency of the Second puncutres = 18/6 = 3
Efficiency of the Third puncutres = 18/18 = 1
Total time = 18/(2 + 3 + 1) = 3