Question

A cold water pipe can fill a swimming pool in 4 hours, and a hot water pipe in 6 hours. If cold water pipe is turned on and hot water pipe is turned on 3 hours later then how long will it take them to fill the pool together?

Answer 1

0.6 of an hour

Explanation:

A cold pipe takes 4h hours so we can assume ¼ of our job is done in one hour.

After 3 hours go by with the cold pipe on, we have ¼ of the job left.

Now we have our hot pipe, which takes 6 hours for the entire pool, so we can assume that it has a rate of ⅙ per hour. Now since these two pipes are working together we can add them.

⅙ + ¼ = ⁵/₁₂

Now we divide.

Since at the start 3 hours had gone by with the cold pipe that would have been ¾ of our time so, 1 - ¾ = ¼

¼ ÷ ⁵/₁₂ = ⅗ or 0.6 of an hour

Answer 2

answer = 5

Explanation:

A cold water pipe can fill a swimming pool in 4 hours

And a hot water pipe in 6 hours.

If cold water pipe is turned on and hot water pipe is turned on 3 hours later

6-4 = 2

2+3 = 5

5 answer