Multiple Choice Questions

Three pipes D E and F can fill a tank in 6 min 8 min and 12 min respectively All the pipes are opene...........

Quantitative Aptitude (MTS) Pipes&cistern

Three pipes, D, E and F, can fill a tank in 6 min, 8 min and 12 min, respectively. All the pipes are opened simultaneously, and

then pipes D and E are closed 3 minutes before tank is fu ll. In how much time will the tank be full?

This questions was previously asked in

SSC MTS 7th July 2022 Shift-3

5 min

3 min

6 min

4 min

- Pipe D can fill the tank in 6 minutes. Its filling rate is 1/6 of the tank per minute.

- Pipe E can fill the tank in 8 minutes. Its filling rate is 1/8 of the tank per minute.

- Pipe F can fill the tank in 12 minutes. Its filling rate is 1/12 of the tank per minute.

- All pipes are opened together initially. Their combined rate: $(1 / 6) + (1 / 8) + (1 / 12) = 1 / 2$ of the tank per minute.

- Since they can fill 1/2 of the tank in 1 minute, they fill the tank in 2 minutes if all remain open.

- However, pipes D and E close 3 minutes before the tank is full.

- In 3 minutes, pipes D, E, and F fill 3/2 of the tank.

- The remaining half of the tank takes 3 more minutes to fill at pipeline F's rate of 1/12 per minute.

Correct Answer: Option 1 - 5 minutes

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