Question

A balloon has two holes. The first hole alone would have made the balloon flat in 9 mins and the second hole would have done it in 6 mins. If air leaks out at a constant rate, how long does it take for both the holes together to make the balloon flat?

• A. 3/2 mins
• B. 7/2 mins
• C. 18/5 mins
• D. 17/4 mins
• E. None of these

Answer 1

The correct option is C

18/5 mins

1 minute’s work for both the holes = $(\frac{1}{9}+\frac{1}{6})=\frac{5}{18}$

So, both the holes will make the balloon flat in $\frac{18}{5}$ mins.