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 3 of 23.
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)
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.
(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)
Gurjit said:
1 decade ago
Why did you write 5/48 as 48/5 ?
Aparna said:
1 decade ago
@gurjit
as per formula,
If A's 1 day's work = 1/n , then A can finish the work in n days.
here also same
c's one days work=5/48
hence he can complete whole work in 48/5 days,tats asked to us
and remember any fraction can also be written in
quotient*remainder/divisor format
when solved 48/5
quotient=9
remainder=3
divisor=5
hence,
9*3/5
as per formula,
If A's 1 day's work = 1/n , then A can finish the work in n days.
here also same
c's one days work=5/48
hence he can complete whole work in 48/5 days,tats asked to us
and remember any fraction can also be written in
quotient*remainder/divisor format
when solved 48/5
quotient=9
remainder=3
divisor=5
hence,
9*3/5
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