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 1 of 4.
Aayush said:
4 years ago
To solve, we need to have at least two scenarios.
Scenario1 Scenario 2
39 * 12 * 5 = 30 * X * 6,
2340 = 180 * X,
2340 ÷ 180 = X,
13 = X.
Scenario1 Scenario 2
39 * 12 * 5 = 30 * X * 6,
2340 = 180 * X,
2340 ÷ 180 = X,
13 = X.
(4)
Nikita said:
6 years ago
Can someone please explain the calculation in detail?
(1)
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)
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)
Vivek singh said:
7 years ago
Thank you all for explaining the solution.
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.
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.
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).
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