Question

You have two pipes P1 and P2 that can fill a large bucket in 4 hours and 2 hours, respectively and you open the pipes at alternate hours.
In the give context, how many hours will it take to fill the bucket if you open P1 first?​

Answer 1

Ans- 3 hours
First hour- 1/4 of the bucket is filled
Second hour- 1/4+1/2 bucket is filled = 3/4 bucket is filled
Third hour 1/4 is left which is filled by P1.

Answer 2

Given:

You have two pipes P1 and P2 that can fill a large bucket in 4 hours and 2 hours, respectively and you open the pipes at alternate hours.

To Find:

In the give context, how many hours will it take to fill the bucket if you open P1 first ?​

Solution:

We know that,

Time taken by P1 = 4 hrs

Time taken by P2 = 2 hrs

This implies that,

In 1 hr, Bucket filled by P1 = $\frac{1}{4}$

In 1 hr, Bucket filled by P2 = $\frac{1}{2}$

If pipes were opened at alternate hours and P1 was first opened,

Bucket after first 3 hrs = $\frac{1}{4} + \frac{1}{2} + \frac{1}{4} = \frac{4}{4} = 1$

Hence, in the given context, it will take 3 hrs to fill the bucket if you open P1 first.