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:
228 comments Page 1 of 23.
A K Burnwal said:
1 month ago
@all.
A - 16 days- A's 1 day work = 1/16.
B- 12 days B's 1 day work = 1/12.
A + B + C - 4 days A +B + C's 1 day work = 1/4.
C alone - 1/4 - (1/16 + 1/12) = 1/4 - 7/48 = 5/48,
C's 1 day work = 48/5 = 9 * 3/5.
A - 16 days- A's 1 day work = 1/16.
B- 12 days B's 1 day work = 1/12.
A + B + C - 4 days A +B + C's 1 day work = 1/4.
C alone - 1/4 - (1/16 + 1/12) = 1/4 - 7/48 = 5/48,
C's 1 day work = 48/5 = 9 * 3/5.
(2)
AKHILESH said:
3 months ago
"Since speed is inversely proportional to time (s=1/t) , we first convert A's time into speed..
After completing the calculations in terms of speed, we convert the result back into time by taking the reciprocal.
Hence, 5/48 becomes 48/5.
After completing the calculations in terms of speed, we convert the result back into time by taking the reciprocal.
Hence, 5/48 becomes 48/5.
(2)
Akash penke said:
11 months 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.
(83)
Akash penke said:
11 months 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.
(23)
Ashlyn cicilia said:
1 year ago
Why is 5/48 take as its reciprocal? Please explain to me.
(37)
Ishita Jain said:
1 year ago
Can also be done like this;
(1/16) *4+ (1/12) * 4 + (1/x) * 4 = 1 (as the total work is 1).
Everybody together completes 1/4 of work in one day.
So, (1/4)*4 = 1.
(1/16) *4+ (1/12) * 4 + (1/x) * 4 = 1 (as the total work is 1).
Everybody together completes 1/4 of work in one day.
So, (1/4)*4 = 1.
(13)
Temesegen demelash said:
1 year ago
Thanks all for helping me to get the answer.
(8)
Tharun A said:
1 year ago
A-----> 16 days.
B ----> 12days.
with the help of C.
AB + C -----> 4 days.
Total work (LCM) = 48.
Efficiency = A-3, B -4, AB + C - 12.
A + B = 7,
AB + C = 12
Then C = 12 - 7 = 5.
C can do work in = Total work/Efficiency = 48/5 = 9*3/5.
B ----> 12days.
with the help of C.
AB + C -----> 4 days.
Total work (LCM) = 48.
Efficiency = A-3, B -4, AB + C - 12.
A + B = 7,
AB + C = 12
Then C = 12 - 7 = 5.
C can do work in = Total work/Efficiency = 48/5 = 9*3/5.
(121)
Siva said:
2 years ago
Good and clear explanation. Thanks all.
(26)
Siva Ranjini said:
3 years ago
A = 48/16=3w/d
B = 48/12=4w/d
C = ?
Total work = 48.
One day completed work = 48/4 = 12.
3+4+? = 12.
C work per day = 5w/d.
C = 48/5.
Ans = 9 3/5 days.
B = 48/12=4w/d
C = ?
Total work = 48.
One day completed work = 48/4 = 12.
3+4+? = 12.
C work per day = 5w/d.
C = 48/5.
Ans = 9 3/5 days.
(113)
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