Question

Pipe A fills a tank in 9 hours. Pipe B fills

the tank in 6 hours. How long would it
take both pipes to fill the tank?

Answer 1

3.6 hours

Explanation:

step 1

we know that

Pipe A fills a tank in 9 hours

so

The 100% of the tank is filled in 9 hours

using proportion

Find out what percentage of the tank is filled in 1 hour

`(100\%)/(9)=(x\%)/(1) \\\\ x=11.11\%`

step 2

we know that

Pipe B fills a tank in 6 hours

so

The 100% of the tank is filled in 6 hours

using proportion

Find out what percentage of the tank is filled in 1 hour

`(100\%)/(6)=(x\%)/(1) \\\\ x=16.67\%`

step 3

we know that

In one hour the percentage of the tank fill with both pipes is equal to

`11.11\%+16.67\%=27.78\%`

using proportion

Find out how long it takes to fill the tank 100%.

`(1)/(27.78\%)=(x)/(100\%)\\\\ x=100/27.78\\ \\x=3.6\ hours`