Question

If Pipe A fills a tank in 4 hours, Pipe B fills a tank in 5 hours, how much time will they take to fill if each pipe is turned on after an interval of 1 hour?

• A. 4 hours 24 minutes
• B. 4 hours 40 minutes
• C. 5 hours 30 minutes
• D. 6 hours 10 minutes

Hint:

When working with rates and intervals, calculate the total contribution of each pipe over each cycle before determining the total time.

Answer 1

The Correct Option is A

Let the time taken to fill the tank be T. - Pipe A fills the tank in 4 hours, so in 1 hour it fills \( \frac{1}{4} \) of the tank. - Pipe B fills the tank in 5 hours, so in 1 hour it fills \( \frac{1}{5} \) of the tank. Each pipe is turned on after an interval of 1 hour. The total filling time is a combination of the times taken by each pipe at different intervals. After solving, we get that the total time to fill the tank is 4 hours 24 minutes.