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 12 of 23.
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).
Ravikumar said:
1 decade ago
How (1/16+1/20)?
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.
Lovely said:
1 decade ago
Why take 1/4 in first step?
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.
Suersh said:
1 decade ago
How 9 3/5?
Adusumalli prasanna said:
1 decade ago
a+b+c=1/4 a's 1st day work = 1/16 b's 1st day work = 1/12.
Therefore c's 1 day work = 1/4-{1/16+1/12) after that 1/4-(12+16/192) {by doing LCM) by dividing 28/192 (by multiplying 2nd table) then we get 1/4-7/48 (by doing LCM).
We get (48-28/192) = 20/192 = 10/96 (dividing with 2 table) we get 5/48. Now please help me why we are taking as 48/5.
Whats the reason explain me clearly please?
Therefore c's 1 day work = 1/4-{1/16+1/12) after that 1/4-(12+16/192) {by doing LCM) by dividing 28/192 (by multiplying 2nd table) then we get 1/4-7/48 (by doing LCM).
We get (48-28/192) = 20/192 = 10/96 (dividing with 2 table) we get 5/48. Now please help me why we are taking as 48/5.
Whats the reason explain me clearly please?
Shivu said:
1 decade ago
Hi thanks all of you solving this problem in easy methods.
Helper said:
1 decade ago
We get 1/x=5/48.
Then we want x. So x=48/5.
Then we want x. So x=48/5.
Bhavana said:
1 decade ago
Firstly take the LCM.
A B ABC.
16 12 4.
LCM IS 48 then ratio is.
A B ABC.
3 4 12.
If a+b-ABC then it's find the value of C = 5 total is 48.
Then divide the 48/5 so simple.
A B ABC.
16 12 4.
LCM IS 48 then ratio is.
A B ABC.
3 4 12.
If a+b-ABC then it's find the value of C = 5 total is 48.
Then divide the 48/5 so simple.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers