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 7 of 23.
Srinivas said:
1 decade ago
C's 1 day work was 5/48. So it can be written as 1/(48/5) and as per the formula if C can do a work in 1/n days then C can complete work in n days which is 48/5. Mixed fraction is written as 9(3/5) = (5*9+3 )/5.
Soumyajit said:
1 decade ago
If I want to solve this problem in this way,
Suppose C can do this work in X day.
Then, in 1 day A can do 1/16, B can do 1/12, C can do 1/X.
Then, 1/16 + 1/12 + 1/X = 1/4.
Can I solved this answer in this way?
Suppose C can do this work in X day.
Then, in 1 day A can do 1/16, B can do 1/12, C can do 1/X.
Then, 1/16 + 1/12 + 1/X = 1/4.
Can I solved this answer in this way?
Amruta said:
1 decade ago
Amruta here,
Lets see this simple method,
Lcm of 16 and 12 is 48.
So A and B will finish their work in 3 and 4 hr.
Answer C will finish in 12 hr.
Hence 12- (3+4) = 5 hr.
Hence answer is 48/5.
Lets see this simple method,
Lcm of 16 and 12 is 48.
So A and B will finish their work in 3 and 4 hr.
Answer C will finish in 12 hr.
Hence 12- (3+4) = 5 hr.
Hence answer is 48/5.
Naim Hussain said:
1 decade ago
For those who can't understand the 5/48 and 48/5 issue, here's my explanation:
C can do 5/48 amount of work in = 1 day.
C can do 1 full work in = 1/5/48 = 48/5 days.
Hope this helps for good.
C can do 5/48 amount of work in = 1 day.
C can do 1 full work in = 1/5/48 = 48/5 days.
Hope this helps for good.
Pavani said:
7 years ago
(A+B+C)'s efficiency - (A+B)'s efficiency = C's efficiency.
(1/4) - (1/16+1/12) = C's efficiency.
5/48 = C's efficiency.
So, the time taken, to complete the total work, by C = 48/5= 9 3/5.
(1/4) - (1/16+1/12) = C's efficiency.
5/48 = C's efficiency.
So, the time taken, to complete the total work, by C = 48/5= 9 3/5.
Chandrakant said:
1 decade ago
Wan we do it this way?
A=16days B=12days, and A+B+C=4 days
So 16+12+C = 4
i.e; 28-4 = c
Hence c = 24days
NOTE: Pls tell me if this method is correct, if not then why?
A=16days B=12days, and A+B+C=4 days
So 16+12+C = 4
i.e; 28-4 = c
Hence c = 24days
NOTE: Pls tell me if this method is correct, if not then why?
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.
Bhimesh said:
6 years ago
Why 5/48 is 48/5 because A can do work in 16 days so his efficiency for 1 day is 1/16.
(which means (work/time)). So same for C's 1-day work is 5/48 and he can complete the work in 48/5.
(which means (work/time)). So same for C's 1-day work is 5/48 and he can complete the work in 48/5.
Gunjan said:
4 years ago
Agree @Truptimayee Bahinipati.
A=15 days.
B= 20 days.
Then the addition of 1/15 + 1/20 =7/60.
7/60 x 4 = 28/60, 28/60 = 14/30, 14/30 = 7/15.
[ 1- 7/15 ] = 8/15.
Answer = 8/15.
A=15 days.
B= 20 days.
Then the addition of 1/15 + 1/20 =7/60.
7/60 x 4 = 28/60, 28/60 = 14/30, 14/30 = 7/15.
[ 1- 7/15 ] = 8/15.
Answer = 8/15.
Sagar said:
1 decade ago
@SHALU
SUPPOSE A,B,C ARE HAVING 10 RUPIEES
WE KNOW DAT A=5 AND B=3 NW WE HAVE TO FIND C
THEN WE WILL ADD BOTH A AND B AND REMOVE FRM TOTAL HERE ALSO SAME WE HAD DONE
UNDERSTOOD
SUPPOSE A,B,C ARE HAVING 10 RUPIEES
WE KNOW DAT A=5 AND B=3 NW WE HAVE TO FIND C
THEN WE WILL ADD BOTH A AND B AND REMOVE FRM TOTAL HERE ALSO SAME WE HAD DONE
UNDERSTOOD
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