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.
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.
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.
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).
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.
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.
Suman said:
9 years ago
If 6 man or 8 woman can repair a road in 28 days. How long 8 man and 2 woman will repair it.
Please solve this.
Please solve this.
Tushar waghchaure said:
8 years ago
For this type of Q, we can simply use an LCM Method.
Take LCM of 39 or 30 =390 this is total time of work that we calculate after that 39 works for 12 Day..but we calculate individuals work so simply divide 390/39=10 unit.
And we need to find how many days 30 workers taken to complete this work so 390/30=13 unit 13 unit is the answer.
Take LCM of 39 or 30 =390 this is total time of work that we calculate after that 39 works for 12 Day..but we calculate individuals work so simply divide 390/39=10 unit.
And we need to find how many days 30 workers taken to complete this work so 390/30=13 unit 13 unit is the answer.
Vivek singh said:
7 years ago
Thank you all for explaining the solution.
Lavanya said:
7 years ago
There is a formula. Here it is a total person(M) * days(D) * hours(H):
M1 * D1 * H1=M2 * D2 * H2.
M1 * D1 * H1=M2 * D2 * H2.
(4)
Lokesh said:
6 years ago
30 x 12 x 5 = 2340.
30 x days x 6 = 2340 (because work is same),
180xdays = 2340,
Days = 13.
30 x days x 6 = 2340 (because work is same),
180xdays = 2340,
Days = 13.
(1)
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