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 1 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.
(12)
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)
Ashlyn cicilia said:
6 months ago
Why is 5/48 take as its reciprocal? Please explain to me.
(23)
Ishita Jain said:
6 months 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.
(10)
Temesegen demelash said:
7 months ago
Thanks all for helping me to get the answer.
(5)
Tharun A said:
8 months 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.
(98)
Siva said:
11 months ago
Good and clear explanation. Thanks all.
(24)
Siva Ranjini said:
2 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.
(102)
Tom said:
2 years ago
(A-B-C) = 1/16-1/12-1/4.
LCM value = 48.
A = 16*3 = 48 (3).
B = 12*4 = 48 (4).
C = 4*12 = 48 (12) .
So,
A = 3.
B = 4.
C = 12.
Then subtract value. i.e AB-C.
AB = 7, C = 12.
12-7 =5,
Answer 48/5.
Final answer 9*3/5.
LCM value = 48.
A = 16*3 = 48 (3).
B = 12*4 = 48 (4).
C = 4*12 = 48 (12) .
So,
A = 3.
B = 4.
C = 12.
Then subtract value. i.e AB-C.
AB = 7, C = 12.
12-7 =5,
Answer 48/5.
Final answer 9*3/5.
(83)
Abhishek Kumar said:
2 years ago
Simple logic;
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.
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.
(115)
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