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:
226 comments Page 3 of 23.
Akash penke said:
1 month ago
Take total work = 48 units (LCM of 16, 12, 4).
A’s efficiency = 48/16 = 3 units/day.
B’s efficiency = 48/12 = 4 units/day.
(A + B + C)’s efficiency = 48/4 = 12 units/day.
So C’s efficiency = 12 − (3 + 4) = 5 units/day.
Time for C = Total work / C’s efficiency = 48/5 = 9 3/5 days = 9.6 days.
A’s efficiency = 48/16 = 3 units/day.
B’s efficiency = 48/12 = 4 units/day.
(A + B + C)’s efficiency = 48/4 = 12 units/day.
So C’s efficiency = 12 − (3 + 4) = 5 units/day.
Time for C = Total work / C’s efficiency = 48/5 = 9 3/5 days = 9.6 days.
(5)
Talib said:
4 years ago
A = 16.
B = 12.
A + B + C = 4.
Total work by a, b, c ie LCM of 16, 12, 4 = 48.
Then A work in 1 day = 48/16 = 3unit.
and B work in 1 day = 48/12 = 4 unit.
And A +B+C work in 1 days = 48/4= 12 unit.
Therefore put value of a and b ie 3 + 4 + c = 12.
ie c work in 1 day = 5 unit.
Therefore total work done by C is 48/5 ans simple and fast method.
B = 12.
A + B + C = 4.
Total work by a, b, c ie LCM of 16, 12, 4 = 48.
Then A work in 1 day = 48/16 = 3unit.
and B work in 1 day = 48/12 = 4 unit.
And A +B+C work in 1 days = 48/4= 12 unit.
Therefore put value of a and b ie 3 + 4 + c = 12.
ie c work in 1 day = 5 unit.
Therefore total work done by C is 48/5 ans simple and fast method.
(3)
St_osagie said:
4 years ago
@All.
Those asking this question: How did come 5/48?
It is called the "rule of flip in time and work" which is how efficiency in piece is derived. Eg. If it takes 3 days for tom to perform a given task. Tom's efficiency in piece is 1/3.
Those asking this question: How did come 5/48?
It is called the "rule of flip in time and work" which is how efficiency in piece is derived. Eg. If it takes 3 days for tom to perform a given task. Tom's efficiency in piece is 1/3.
(2)
Vaishnavi Deshpande said:
3 years ago
Why do not we consider work done by A+B in 4 days and then subtract it from 1 to get work done by C in 4 days? Please anyone explain me.
(2)
AMIT said:
1 decade ago
How the fractional 7/48 arrived?
(1)
Deepika said:
1 decade ago
How is last step is taken 5/48 is reversed to 48/5?
(1)
Ganesh said:
10 years ago
Total work is 48 units.
A can do work in 16 days.
It means A completes 3 units per day.
B can do work in 12 days.
It means B completes 4 units per day.
Now A and B is helped by C and completed work in 4 days.
It means A, B and C together doing 12 units per day.
It means A+B+C = 12.
Sub A and B values.
3+4+C = 12.
C = 5.
It means C completes 5 units per day.
For 48 units?
Answer: 48/5.
A can do work in 16 days.
It means A completes 3 units per day.
B can do work in 12 days.
It means B completes 4 units per day.
Now A and B is helped by C and completed work in 4 days.
It means A, B and C together doing 12 units per day.
It means A+B+C = 12.
Sub A and B values.
3+4+C = 12.
C = 5.
It means C completes 5 units per day.
For 48 units?
Answer: 48/5.
(1)
Ishwar said:
5 years ago
Because time is inversely proportional to Rate and your calculated rate is 5/48 (this is C`s rate at which C working so).
(1)
Sangmesh said:
4 years ago
5/48 how this came? Please explain.
(1)
Nil said:
3 years ago
How 48/5 is written as 9*3/5? Please explain.
(1)
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