Aptitude - Chain Rule - Discussion
Discussion Forum : Chain Rule - General Questions (Q.No. 5)
5.
39 persons can repair a road in 12 days, working 5 hours a day. In how many days will 30 persons, working 6 hours a day, complete the work?
Answer: Option
Explanation:
Let the required number of days be x.
Less persons, More days (Indirect Proportion)
More working hours per day, Less days (Indirect Proportion)
| Persons | 30 | : | 39 |  |
:: 12 : x |
| Working hours/day | 6 | : | 5 |
30 x 6 x x = 39 x 5 x 12
 x = |
(39 x 5 x 12) |
| (30 x 6) |
x = 13.
Discussion:
32 comments Page 3 of 4.
Mithilesh said:
1 decade ago
1 person can do this work in 39*12*5 = 2340 hrs.
Hence 30 persons will do in 2340/30 = 78 hrs = 78/6 13 days.
I think its very understandable.
Hence 30 persons will do in 2340/30 = 78 hrs = 78/6 13 days.
I think its very understandable.
Aranya said:
1 decade ago
Persons 30 : 39 :: 12 : x.
Working hours/day 6 : 5.
How did we get the following line?
30 x 6 x x = 39 x 5 x 12.
Working hours/day 6 : 5.
How did we get the following line?
30 x 6 x x = 39 x 5 x 12.
H.R said:
1 decade ago
@Anila.
Persons*days*hours = Persons*days*hours.
Persons*days*hours = Persons*days*hours.
Sachin prakash srivastava said:
1 decade ago
M1D1H1 M2D2H2
------ = ------
W1 W2
Where,
M = No.of Men
D = No.of Days
H = No.of Hours
W = Amt of Work done.
In this problem, if we apply this equation,
39*12*5 = 30*6*x
x=13 is the answer.
------ = ------
W1 W2
Where,
M = No.of Men
D = No.of Days
H = No.of Hours
W = Amt of Work done.
In this problem, if we apply this equation,
39*12*5 = 30*6*x
x=13 is the answer.
Ravi Teja P said:
1 decade ago
@subhi.
12 men completes a piece of work in 66 days.
=> Work done by 12men/day = (1/66)th part.
=> Work done by 1man/day = (1/66*12)= (1/792)th part.
Similarly,
15 women completes the work in 66 days.
=> Work done by 15women/day = (1/66)th part.
=> Work done by 1women/day = (1/66*15)= (1/990)th part.
Now.. 24men and 3women together.
So, calculate work done by (24men and 3women)/day.
=> (24/792)+(3/990)
=> (1/33)+(1/330)
=> (11/330) = 1/30.
=> Work done by (24men and 3women)/day= (1/30)th part.
=> Total no.of days to complete the work is 30 days.
12 men completes a piece of work in 66 days.
=> Work done by 12men/day = (1/66)th part.
=> Work done by 1man/day = (1/66*12)= (1/792)th part.
Similarly,
15 women completes the work in 66 days.
=> Work done by 15women/day = (1/66)th part.
=> Work done by 1women/day = (1/66*15)= (1/990)th part.
Now.. 24men and 3women together.
So, calculate work done by (24men and 3women)/day.
=> (24/792)+(3/990)
=> (1/33)+(1/330)
=> (11/330) = 1/30.
=> Work done by (24men and 3women)/day= (1/30)th part.
=> Total no.of days to complete the work is 30 days.
Subhi said:
1 decade ago
I have a question plz answer:
12 men or 15 women completes a piece of work in 66 days, 24 men and 3 women together can complete in in how many days?
12 men or 15 women completes a piece of work in 66 days, 24 men and 3 women together can complete in in how many days?
Simha said:
1 decade ago
There is simple formula for this type of questions:
M1D1H1 M2D2H2
------ = ------
W1 W2
Where,
M = No.of Men
D = No.of Days
H = No.of Hours
W = Amt of Work done.
In this problem, if we apply this equation,
39*12*5 = 30*6*x
x=13 is the answer.
M1D1H1 M2D2H2
------ = ------
W1 W2
Where,
M = No.of Men
D = No.of Days
H = No.of Hours
W = Amt of Work done.
In this problem, if we apply this equation,
39*12*5 = 30*6*x
x=13 is the answer.
Adeel Jabbar said:
1 decade ago
I thing the easy way to solve this out is below.
39 12 5
30 x 6
after cross multiplication, we will have
39 1
3 x
According to rule
39x = 3
x = 3 / 39
now due to indirect relation we will change the above equation as::: x = 39/3 which results ===13
Thanks
39 12 5
30 x 6
after cross multiplication, we will have
39 1
3 x
According to rule
39x = 3
x = 3 / 39
now due to indirect relation we will change the above equation as::: x = 39/3 which results ===13
Thanks
Pratswinz said:
1 decade ago
Hope you all understand....
First codition=total hours to complete the work=39 persons * 12 days * 5 hr
Second codition=total hours to complete the work=30 persons * x days * 6 hr
since the work is still the same so
39*12*5=30*x*6
x=13
First codition=total hours to complete the work=39 persons * 12 days * 5 hr
Second codition=total hours to complete the work=30 persons * x days * 6 hr
since the work is still the same so
39*12*5=30*x*6
x=13
Miyyapuram said:
1 decade ago
Ny cross multiplication method i didn't get correct ans.....
39---->12*5hrs
then 30---->x*6hrs
Now 30*12*5=39*x*6
then 30*12*5/39*6=x......... then i got 100/13........
is it correct or wrong
39---->12*5hrs
then 30---->x*6hrs
Now 30*12*5=39*x*6
then 30*12*5/39*6=x......... then i got 100/13........
is it correct or wrong
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