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 2 of 4.
Nagendra kumbar said:
9 years ago
1st section = 39 P *12 D *5H
2nd section =30 P * X D * 6H
Then ,
39 * 12 * 5 = 30 * X * 6,
X = (39 * 12 * 5)/(30 * 6),
X = 13.
2nd section =30 P * X D * 6H
Then ,
39 * 12 * 5 = 30 * X * 6,
X = (39 * 12 * 5)/(30 * 6),
X = 13.
Vaibhav said:
9 years ago
39 person 1 day work is ---> 1/12.
39 person complete total work in 1/12 * 1/5.
1person complete in 1/12 * 1/5 * 1 * 39 ---> eq1.
Similarly
30 person one day work let be n.
So they take 1/n.
Total time 1/n * 1/6hour.
1person one day work 1/30 * 1/n * 1/6 ---> eq2.
Person efficiency are same so,
Equation 1 = eqution2.
Calculate value of n will obtain.
39 person complete total work in 1/12 * 1/5.
1person complete in 1/12 * 1/5 * 1 * 39 ---> eq1.
Similarly
30 person one day work let be n.
So they take 1/n.
Total time 1/n * 1/6hour.
1person one day work 1/30 * 1/n * 1/6 ---> eq2.
Person efficiency are same so,
Equation 1 = eqution2.
Calculate value of n will obtain.
Sanjay said:
9 years ago
You have taken this as:
Persons --> 30 : 39 :: 12 : x,
Working hours/day --> 6 : 5,
Why it can't be like,
Persons --> 39 : 30 :: 12 : x,
Working hours/day --> 5 : 6,
So, I get the equation as (39 * 5 * x) = (30 * 6 * 12).
Persons --> 30 : 39 :: 12 : x,
Working hours/day --> 6 : 5,
Why it can't be like,
Persons --> 39 : 30 :: 12 : x,
Working hours/day --> 5 : 6,
So, I get the equation as (39 * 5 * x) = (30 * 6 * 12).
Pavan Power star fan said:
9 years ago
Here 39 men work for 5 * 12 hrs totally to complete the road.
Let x be the no of days that 30 people work, then the no of hours 30 people take to complete road is 6x hours.
The amount of work done is inversely proportional to no. of working hours.
i.e
(39/30) = (6x/60).
x = 13.
Hope you understand.
Let x be the no of days that 30 people work, then the no of hours 30 people take to complete road is 6x hours.
The amount of work done is inversely proportional to no. of working hours.
i.e
(39/30) = (6x/60).
x = 13.
Hope you understand.
Nilesh Tripathi said:
9 years ago
@Pratswinz.
You explained it in the best way. Thanks, it's very helpful.
You explained it in the best way. Thanks, it's very helpful.
Santosh k said:
9 years ago
For the first statement Total man hours = 39*12*5.
Again for the second statement man hours = 30*X*6.
Equating both equation X = 39*12*5/30*X*6 = 13 days.
Again for the second statement man hours = 30*X*6.
Equating both equation X = 39*12*5/30*X*6 = 13 days.
Anila said:
2 decades ago
The equation is 30 x 6 x x = 39 x 5 x 12 not clear to understand.
Please explain it clearly. When I solved this problem I got equation as 39 x 12 x 5 = 30 x x x 6.
How come you got that equation?
Please explain it clearly. When I solved this problem I got equation as 39 x 12 x 5 = 30 x x x 6.
How come you got that equation?
Lipu said:
1 decade ago
39 persons can repair in 60 hours.
1 person can do in 60*39 hours.
30 persons can do it in(60*39)/30 hours = 78 hours.
If they work 6 hours a day.
So no.of days is 78/6 = 13 days.
1 person can do in 60*39 hours.
30 persons can do it in(60*39)/30 hours = 78 hours.
If they work 6 hours a day.
So no.of days is 78/6 = 13 days.
Nisha said:
1 decade ago
The sum of infinity of a geometric series is 60. If its first term is 80, find the common ratio? can you give the answers?
Raja said:
1 decade ago
The total number of hours of work is 39(people)*60 (Working 60 hours) = 2340.
Now 30 people working 6 hours so the number of days are 2340/180 = 13.
Now 30 people working 6 hours so the number of days are 2340/180 = 13.
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