Aptitude - Chain Rule - Discussion
Discussion Forum : Chain Rule - General Questions (Q.No. 14)
14.
36 men can complete a piece of work in 18 days. In how many days will 27 men complete the same work?
Answer: Option
Explanation:
Let the required number of days be x.
Less men, More days (Indirect Proportion)
27 : 36 :: 18 : x 
27 x x = 36 x 18
 x = |
36 x 18 |
| 27 |
x = 24.
Discussion:
14 comments Page 1 of 2.
Robert said:
1 decade ago
Give the explanation fully.
Snehal said:
1 decade ago
But if we do it like this,
36 men - 18 days.
27 men - ?.
By cross multiplication, the answer will be different.
36 men - 18 days.
27 men - ?.
By cross multiplication, the answer will be different.
Hary said:
1 decade ago
Snehal,.
Here we cannot cross multiply like this.
Because, No of men is inversely proportional to no of days.
So, No of men is directly proportional to 1/no of days.
We should write it as.
No of men=k/no of days.
36 = k / 18 ------- (1).
27 = k / ? ------- (2).
Dividing (1) and (2).
36/27 = ?/18.
? = 36*18/27.
No of days = 24.
Here we cannot cross multiply like this.
Because, No of men is inversely proportional to no of days.
So, No of men is directly proportional to 1/no of days.
We should write it as.
No of men=k/no of days.
36 = k / 18 ------- (1).
27 = k / ? ------- (2).
Dividing (1) and (2).
36/27 = ?/18.
? = 36*18/27.
No of days = 24.
Davinder said:
1 decade ago
please give exoplanation fully.........
i am agree with snehal
i am agree with snehal
Davinder said:
1 decade ago
please give exoplanation fully.........
i am agree with snehal
i am agree with snehal
Shobhit said:
1 decade ago
36 men 1 day work = 1/18
1 men 1 day work = 1/18 *1/36
now 27 men 1 day work = 1/18 * 1/36 *27
multiply and cancel u will get 24 ...easy/.
1 men 1 day work = 1/18 *1/36
now 27 men 1 day work = 1/18 * 1/36 *27
multiply and cancel u will get 24 ...easy/.
Parmeshwar mathpati said:
1 decade ago
But if we do it like this,
36 men - 18 days.
27 men - ?.
By cross multiplication, the answer will be different.
36 men - 18 days.
27 men - ?.
By cross multiplication, the answer will be different.
Udaya said:
1 decade ago
36 men 18 days= 1 (work)
1 man 1 day=1/36*18
=>1/648
Hence, 27 men=1/648*27=1/24 days.
1/24 is 1 day work of 27 men.
So 27 men complete the work in 24 days.
1 man 1 day=1/36*18
=>1/648
Hence, 27 men=1/648*27=1/24 days.
1/24 is 1 day work of 27 men.
So 27 men complete the work in 24 days.
Priya said:
1 decade ago
Let no of days be x.
36 men do work in 18 days.
27 men do work in x days.
As no of men decrease Therefore,
Days increases so,
x = 18*36/27 = 24.
36 men do work in 18 days.
27 men do work in x days.
As no of men decrease Therefore,
Days increases so,
x = 18*36/27 = 24.
Rajkumar said:
1 decade ago
@Snehal.
Just think in normal way if it is cross multiplying the answer is 13 (APPROX) , as men decrease days should increase it is not happening. So above explanation is true.
Just think in normal way if it is cross multiplying the answer is 13 (APPROX) , as men decrease days should increase it is not happening. So above explanation is true.
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