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A tire has 3 punctures. The first puncture alone could expel the air of that tire in 7 minutes, second alone in 14 minutes and third alone in 28 minutes. If the air exits at a constant rate, then how much time (in minutes) will it take for all the punctures to expel the entire air from the tire?

A tire has 3 punctures. The first puncture alone could expel the air of that tire in 7 minutes, second alone in 14 minutes and third alone in 28 minutes. If the air exits at a constant rate, then how much time (in minutes) will it take for all the punctures to expel the entire air from the tire? Correct Answer 4

Given:

Puncture expel air in 7 min, 14 min, 28 min

Formula:

Total work = Efficiency × Time taken

Calculation:

Let the total capacity of tire be 28 units

⇒ Efficiency of 1st puncture = 28/7 = 4 units/min

⇒ Efficiency of 2nd puncture = 28/14 = 2 units/min

⇒ Efficiency of 3rd puncture = 28/28 = 1 unit/min

∴ Required time = 28/(4 + 2 + 1) = 4 min

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