Question

Tap A can fill a tank in 30 minutes and tap B can fill the same tank in 60 minutes. If both the taps are opened together for 5 minutes, and after that tap A stopped working, then in how much time remaining part of the tank can be filled?
1. 20 minutes
2. 25 minutes
3. 30 minutes
4. 45 minutes

Answer 1

Correct Answer - Option 4 : 45 minutes

Given:

Tap A can fill the tank = 30 minutes

Tap B can fill the tank = 60 minutes
Concept:

If a tap can fill a tank in x hours, then the tank filled by the tap in 1 hour = 1 / x of the total tank.

Calculation:

Part of the pool filled by both taps in 5 minutes

⇒ 5 × [(1 / 30) + (1 / 60)]

⇒ 5 × (2 + 1) / 60

⇒ 3 / 12

⇒ 1 / 4

Remaining part = 1 – 1 / 4 = 3 / 4 that is filled by second tap.

Required time = 60 × 3 / 4

⇒ 45 minutes

∴ The tank can be filled in 45 minutes.