# CAT Practice : Pipes cisterns, Work time

You are here: Home  CAT Questionbank   CAT Quant  Arithmetic: Pipes cisterns  Question 20
Classic Work - Time Question!!

## Fetching Water

Q.20: Bibhor takes 3 hours to fetch as much water as Ahmed can fetch in 2 hours. Deepak takes 5 hours to fetch as much water as Bibhor can fetch in 4 hours. A tank takes 20 hours to fill if all work together. What time would Bibhor take to fill the tank alone?
1. 50 h
2. 56 h
3. 77 h
4. 66 h

Choice D. 66 h

## Detailed Solution

Let the work done by Ahmed be 60 (LCM of 2,3,4,5)

So, work done per hour by:

Ahmed – $\frac{60}{2}$ = 30
Bibhor – $\frac{60}{3}$ = 20

Bibhor in 4 hours – 20 x 4 = 80

Deepak – $\frac{80}{5}$ = 16

Therefore, total work done in an hour = 30 + 20 + 16 = 66

If all 3 work for 20 hours, total work done = 66 x 20

If Bibhor alone has to work, time taken to do 66 x 20 of work = $66 * \frac{20}{20}$ (work done by Bibhor in 1 hour) = 66 hour

## Our Online Course, Now on Google Playstore!

### Fully Functional Course on Mobile

All features of the online course, including the classes, discussion board, quizes and more, on a mobile platform.

### Cache Content for Offline Viewing

Download videos onto your mobile so you can learn on the fly, even when the network gets choppy!

## More questions from Pipes Cisterns, Work Time

Mathematicians are creatures of habit. This topic has been called Pipes and Cisterns because someone named it like it long ago. Pipes and Tanks would be much better - at least makes it sound like wartime.