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?
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 6 of 7.
Math Master said:
1 decade ago
Better you do like this:
3 pumps take 16 hrs total (8 Hrs a day)
If 1 pump will be working then, it will need 16*3=48 hrs
1 pump need 48 Hrs
If I contribute 4 pumps then
48/4=12 hrs.
3 pumps take 16 hrs total (8 Hrs a day)
If 1 pump will be working then, it will need 16*3=48 hrs
1 pump need 48 Hrs
If I contribute 4 pumps then
48/4=12 hrs.
Sivakumar said:
1 decade ago
a:b::c:d=>bc=ad
Shaunak said:
1 decade ago
It's simple direct and inverse ratio theory. You can apply unitary method,but that'll take a hell lot of time.
Naveen moorthy said:
1 decade ago
As tank are Same.
So 3x8=24 hours required for 1 day for that tank.
So hrs will be same.
For 4 tanks, 4x6=24 for 2 days.
If it 1 day, 6x2=12 hours.
So 3x8=24 hours required for 1 day for that tank.
So hrs will be same.
For 4 tanks, 4x6=24 for 2 days.
If it 1 day, 6x2=12 hours.
Imraz said:
1 decade ago
3 pumps 8 hours 2 days =work
3*8*2=work----->eqn1
now to complete the same work with 4 pumps in 1 day how many hours are required? lets take the hours required as x. then we can write the same work as
4 pump x hours 1 day =work
4*x*1=work ---->eqn2
equating both equation
3*8*2=4*x*1
x=48/4
x=12 hours
3*8*2=work----->eqn1
now to complete the same work with 4 pumps in 1 day how many hours are required? lets take the hours required as x. then we can write the same work as
4 pump x hours 1 day =work
4*x*1=work ---->eqn2
equating both equation
3*8*2=4*x*1
x=48/4
x=12 hours
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.
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.
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