Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 2)
2.
A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:

9 1 days
5

9 2 days
5

9 3 days
5

10
Answer: Option
Explanation:

(A + B + C)'s 1 day's work = 1 ,
4

A's 1 day's work = 1 ,
16

B's 1 day's work = 1 .
12

Therefore C's 1 day's work = 1 - ( 1 + 1 ) = ( 1 - 7 ) = 5 .
4 16 12 4 48 48

So, C alone can do the work in 48 = 9 3 days.
5 5

Discussion:
224 comments Page 17 of 23.

Shweta Narkhede said:   9 years ago
Thank you very much friends, I got lots of help because of yours discussion with this topic.

Amogh said:   9 years ago
A can complete 1/16th of the work in 1 day.

B can complete 1/12th of the work in 1 day.

Let C complete 1/Xth of the work in 1 day.

So, A, B & C can complete (1/16 + 1/12 + 1/X)th part of the work in 1 day.

Therefore in 4 days, they together can complete = 4*(1/16 + 1/12 + 1/X)th part of the work . Always remember & denote work completed as 1.

On solving 4*(1/16 + 1/12 + 1/X) = 1, you can get the value of x which is the number of days taken by C to do the work.

Hope it helps you.

Sunny said:   9 years ago
A's efficiency = 3, and B's efficiency =4, so (3 + 4) = 5 then C's efficiency (12 - 7) =5, So total work take LCM of (16, 12, 4) = 48, so C alone finished the work 48/5.

Asshok007 said:   9 years ago
@Shantanu

Thank you, you are right.

Actually, A can solve in 16 days for one day it will be 1/16. if we take for 2 days work it will become 2/16. in the same way the work done by c per day is 5/48. If you want total work done by 'c' just reverse the fraction like 48/5.

Ex: THE TOTAL WORK DONE BY 'B' IS IN 12DAYS, FOR ONE DAY 12,IN THE SCENE 12/1. You should remember that 5/48 is the work done by 'c' in one day.

Lakshmi said:   9 years ago
Thanks for clarifying the solution @Ajay.

Ishwar shrestha said:   9 years ago
Guys don't be confused.

A can do in 16 days.
B can do in 12 days.
A B & C can do in 4 days.

So,
Total work is to be done is 48.
( lcm of all)
Then A's efficiency is 3.
B's effc is 4.
A B n C effc is 12.
So, A + B + C = 12
4 + 3 + C = 12
7 + c = 12
C = 5.

Then 5/48 or 48/5.

Shruti said:   8 years ago
I didn't get still that how 5/48 came from 28/192, actually, I don't know the basics to solve maths so please explain.

Lokesh said:   8 years ago
How is possible at 5/48 write 48/5? please solve it for me.

Ammu said:   8 years ago
@Shruti.

A's one day work = 1/16.
B's one day work = 1/12.
with the help of C , they finished in 4 days.
So, A+B+C=4 days,
Therefore, (A+B+C)'s one day work = 1/4.
If C alone is = X.
then 1/16+1/12+X = 1/4,
X= 1/4-(1/16+1/12) {Lcm of 16, 12 is 48 and by the cross multiplication will get 7/48}
= 1/4-7/48,
= 12-7/48,
= 5/48,
C's one day work = 5/48.

Gokul said:   8 years ago
According to me,
a+b+c=4
a=16
b=12
c=?

C = a * b/b-c,
=16 * 12/16-12,
= 16 * 12/4,
=4 * 12 = 48.

Am I correct?


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