Taps A and B can fill a tank in 12 min and 15 min respectively. If both are opened and A is closed after 3 min, how long will it take for B to fill the tank?

Foundation

Mathematics Foundation

Mixture

Time Speed Distance

Question

Taps A and B can fill a tank in 12 min and 15 min respectively. If both are opened and A is closed after 3 min, how long will it take for B to fill the tank?

A

8 min 5 s

B

7 min 45 s

C

8 min 15 s

D

7 min 15 s

LiveFree JEE Main Previous Year Online Papers Live Free JEE Advance Previous Year Online Papers

JEE Advance

College PredictorLive

Know your College Admission Chances Based on your Rank/Percentile, Category and Home State.

Get your JEE Main Personalised Report with Top Predicted Colleges in JoSA

In a minute (A + B) fill $\frac{1}{12} + \frac{1}{15} = \frac{9}{60}$

In 3 min they fill $3 \times \frac{9}{60} = \frac{27}{60}$ part of tank

Remainig part = $1 - \frac{27}{60} = \frac{33}{60}$

So, B will take $\frac{33}{60} \times 15$ = 8 min 15 s.