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:
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 |
 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 19 of 23.
Parthasarathy said:
1 decade ago
@HIREN.
If A can do some work in N days.
So A can do that same work in one day =1/N.
So the answer 5/48 obtained by (1/4) - (1/16+1/4) =5/48.
So you should consider this as only 48/5.
If A can do some work in N days.
So A can do that same work in one day =1/N.
So the answer 5/48 obtained by (1/4) - (1/16+1/4) =5/48.
So you should consider this as only 48/5.
Amit.J said:
1 decade ago
A+B+C=4 day.
A=16 day.
B=12 day.
C=?
Formula..
A+B+C=A*B*C/AB+BC+CA
4=192C/192+28C
4(192+28C)=192C
768+112C=192C
768=192C-112C
768=80C
768/80=C
C=48/5 Ans.
A=16 day.
B=12 day.
C=?
Formula..
A+B+C=A*B*C/AB+BC+CA
4=192C/192+28C
4(192+28C)=192C
768+112C=192C
768=192C-112C
768=80C
768/80=C
C=48/5 Ans.
Hiren said:
1 decade ago
Why you write 48/5 from 5/48.
Suryakiran varma said:
1 decade ago
Look,
A can do a work in 16 days,so his one day work will be=1/16
and also B's one day work will be =1/12;
in the same way A,B,C together do a work in 4 days,so thier one day work will be=1/4
C 's one day work will be=(A+B+C)'s one day work - (A+B)'s one day work
i.e..
=(1/4)-(1/16+1/12)
=(1/4)-(7/48)
=(5/48)
thus,C's one day work is = 5/48,
so,he can do the work in 48/5 days..i.e..9 3/5.
A can do a work in 16 days,so his one day work will be=1/16
and also B's one day work will be =1/12;
in the same way A,B,C together do a work in 4 days,so thier one day work will be=1/4
C 's one day work will be=(A+B+C)'s one day work - (A+B)'s one day work
i.e..
=(1/4)-(1/16+1/12)
=(1/4)-(7/48)
=(5/48)
thus,C's one day work is = 5/48,
so,he can do the work in 48/5 days..i.e..9 3/5.
Rajasekar said:
1 decade ago
How 5/48 is written 48/5?
Anshu said:
1 decade ago
"A" can do the 1/16 of the work in a day.
"B" can do the 1/12 of the work in a day.
A + b + c = 1/4 of the work.
1/16 + 1/12 + c = 1/4.
3/48 + 4/ 48 + c = 1/4.
7/48 + c = 1/4.
C = 1/4 - 7/48 = 12-7/48 = 5/48.
C can do 5/48 of the work per day.
Therefore he can complete his work on 48/5 days = 9 3/5.
"B" can do the 1/12 of the work in a day.
A + b + c = 1/4 of the work.
1/16 + 1/12 + c = 1/4.
3/48 + 4/ 48 + c = 1/4.
7/48 + c = 1/4.
C = 1/4 - 7/48 = 12-7/48 = 5/48.
C can do 5/48 of the work per day.
Therefore he can complete his work on 48/5 days = 9 3/5.
Amrut said:
1 decade ago
C s one day work is 5/48. But how you came to 48/5, I mean C finish job in 48/5 days. Is there any formula for this result?
Udita said:
1 decade ago
@Saquib Ali.
Please explain the following step.
Units of work in a day by a = 48x/16 = 48 units.
Please explain the following step.
Units of work in a day by a = 48x/16 = 48 units.
Tiny said:
1 decade ago
@chandrakant.
Your method is totaly wrong. When c comes in right hand side it will become negative.
Your method is totaly wrong. When c comes in right hand side it will become negative.
Indian said:
1 decade ago
@ Ovii
Thanks for explanation, Now I understood well.
Thanks for explanation, Now I understood well.
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