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 12 of 23.
Suersh said:
1 decade ago
How 9 3/5?
Ramakrishna said:
1 decade ago
@RaviKumar.
We have A+C = 4 -->A+C 1 day work = 1/4.
B+C = 4 --> B+C 1 day work = 1/4.
We add (A+C)+(B+C) = (1/4)+(1/4).
A+B+2C = (4+4)/(4*4) = 8/16 = 1/2.
A+B+2C = 1/2.
A+B+C = 1/(2*2) = 1/4.
That's it A+B+C = 1/4 -->A+B+C's 1 day work.
A's 1 day work = 1/16.
B's 1 day work = 1/12.
C's 1 day work = "We have A+B+C's 1 day work then subtraction to(A's 1 day+B's 1 day)".
= (A+B+C)-(A+B).
= (1/4)-(1/16+1/12).
= 1/4-(7/48) = 5/48.
C's 1 day work= 5/48 then C can do job= 48/5.
= Formula :: X 1 day task 1/n, x can do task n;
=48/5---> (9*5)+3/5---> 9 3/5.
=9 3/5.
We have A+C = 4 -->A+C 1 day work = 1/4.
B+C = 4 --> B+C 1 day work = 1/4.
We add (A+C)+(B+C) = (1/4)+(1/4).
A+B+2C = (4+4)/(4*4) = 8/16 = 1/2.
A+B+2C = 1/2.
A+B+C = 1/(2*2) = 1/4.
That's it A+B+C = 1/4 -->A+B+C's 1 day work.
A's 1 day work = 1/16.
B's 1 day work = 1/12.
C's 1 day work = "We have A+B+C's 1 day work then subtraction to(A's 1 day+B's 1 day)".
= (A+B+C)-(A+B).
= (1/4)-(1/16+1/12).
= 1/4-(7/48) = 5/48.
C's 1 day work= 5/48 then C can do job= 48/5.
= Formula :: X 1 day task 1/n, x can do task n;
=48/5---> (9*5)+3/5---> 9 3/5.
=9 3/5.
Lovely said:
1 decade ago
Why take 1/4 in first step?
Jack said:
1 decade ago
B's 1 day's work = 1/12.
Therefore 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 = 93 days.
Therefore 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 = 93 days.
Ravikumar said:
1 decade ago
How (1/16+1/20)?
Lokesh said:
1 decade ago
Why C-A+B?
Therefore C's 1 day's work = (1/4)-(1/16+1/20).
Therefore C's 1 day's work = (1/4)-(1/16+1/20).
Phani Kumar said:
1 decade ago
Can explain 5/48 has come?
Ayush said:
1 decade ago
Can anybody explain the basic to know how the 48/5 comes?
Anurag said:
1 decade ago
Can anybody explain LCM method like this?
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.
Mohammed aqib said:
1 decade ago
In equation 5/48 how did 5 arise?
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