Aptitude - Chain Rule - Discussion

Discussion Forum : Chain Rule - General Questions (Q.No. 1)
1.
3 pumps, working 8 hours a day, can empty a tank in 2 days. How many hours a day must 4 pumps work to empty the tank in 1 day?
9
10
11
12
Answer: Option
Explanation:

Let the required number of working hours per day be x.

More pumps, Less working hours per day (Indirect Proportion)

Less days, More working hours per day (Indirect Proportion)

Pumps 4 : 3 :: 8 : x
Days 1 : 2

4 x 1 x x = 3 x 2 x 8

x = (3 x 2 x 8)
(4)

x = 12.

Discussion:
69 comments Page 3 of 7.

Raja said:   1 decade ago
@maher. I am just asking where is the concept of chain rule (indirect propprtion) approach.

Sudheer said:   1 decade ago
Imraz said well.

Yogendra said:   1 decade ago
Thanks imraz your method is very easy to understand.

Maths lover said:   1 decade ago
@math master and all.

Your approach is right because fortunately question is asking of 1 day. If not. Then we have to divide the answer by number of days. So people take care of that also.

Kuntal Paul said:   1 decade ago
Mathmaster method is so simple and effective.

Ram chowdary m said:   1 decade ago
Math master really thank you sir your said easy and simple method.

Hari said:   1 decade ago
Yes it's very easy to understand solved by Mathmaster. ThanQ.

I can't understand your question Mr. Akhilesh sahu.

Sanjit said:   1 decade ago
As a lay man I liked the DPH formula of meher.

Thanks.

Sandeep said:   1 decade ago
GIVEN: 3 pumps' 1 hour's work= 1/16
SOLUTION : 1 pump's 1 hour's work= 1/48
4 pumps' 1 hour's work= (1/48)*4 = 1/12
hence 4 pumps will finish the work in 12 hours

Kartik said:   1 decade ago
Thanks to mathmaster.


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