Note 1
##### Take Note:

Take a note while surfing.

##### Note With Ink

Give your Note a Colorful Tag.

##### Easy to Access

Stay on same information and in Sync wherever you are.

Note 2
##### Take Note:

Organize your information,It may take Shape.

##### Easy to Access

Easy to pull up your content from anywhere anytime.

Note 3
##### Take Note:

Don't Let information to miss,Because it take shape

##### Note With Ink

Simple an Easy Way to take a note.

##### Easy to Access

Get the same in next visit.

# Arithmetic Aptitude :: Pipes & Cistern

## 9. A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both taps are opened simultaneously, then after how much time will the cistern get filled ?

Explanation :

Time taken by tap A to fill the cistern=4 hrs
so work done by tap A in 1 hour = 1/4th
Time taken by tap B to empty the full cistern = 9 hours
so work done by tap B in 1 hour = 1/9th
=> Work done by (A + B) in 1 hour=(1/4 - 1/9)=5/36
Therefore, the tank will fill the cistern = 36/5 hours=7.2 hours.