Question

of the cistern
A cistem can be filled by a tap in 7 hours and emptied by an outlet pipe in 9 hours.
How long will it take to fill the cistern if both the tap and the pipe are opened
together
​

Answer 1

Given:

✰ A cisten can be filled by a tap in 7 hours

✰ A cisten can be emptied by an outlet pipe in 9 hours.

To find:

✠ How long will it take to fill the cistern if both the tap and the pipe are opened together.

Solution:

Let's understand the concept here! First we will find tap's one hour work and then we will find outlet pipe's 1 hour work. After that, we will add both one hour work of tap and the one hour work of outlet pipe to find the time taken to fill the cistern if both the tap and the pipe are opened together.

Steps:

• A cisten can be filled by a tap in 7 hours

⟹ Tap's 1 hour work = 1/7

• A cisten can be emptied by an outlet pipe in 9 hours.

⟹ Outlet pipe's 1 hour work = 1/9

➤ They work together in 1 hour = 1/7 + 1/9

➤ They work together in 1 hour = (9+7)/63

➤ They work together in 1 hour = 16/63

They can together complete work in 63/16 hours

= 3.9375 hours

∴ It will take 3.94 hours to fill the cistern if both the tap and the pipe are opened together.

Answer 2

Step-by-step explanation:

3.9375 is a right answer