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 16 of 23.
Vamsi said:
1 decade ago
LCM of numbers 16, 12, 4 = 48.
16 is 3 times.
12 is 4 times.
4 is 12 times.
a-16d-3 units.
b-12d-4 units.
c-?- ? units.
a+b+c = 12 units .
Total work complete 12 units.
a+b complete 7.
Remaining work c 5.
= total/remaining work, 48/5 = 9.6 this is also written 9 3/5.
16 is 3 times.
12 is 4 times.
4 is 12 times.
a-16d-3 units.
b-12d-4 units.
c-?- ? units.
a+b+c = 12 units .
Total work complete 12 units.
a+b complete 7.
Remaining work c 5.
= total/remaining work, 48/5 = 9.6 this is also written 9 3/5.
Jansi said:
1 decade ago
Hello Mr. Khan,
You can refer June -19th tuesday Mr. Amit.J has explained good. He given clear explanation.
But Mr.Amit you had used this formula, (a+b+c) = a*b*c/ (ab+bc+ca). Always we can use this formula or any other restriction is there. Can you explain me?
You can refer June -19th tuesday Mr. Amit.J has explained good. He given clear explanation.
But Mr.Amit you had used this formula, (a+b+c) = a*b*c/ (ab+bc+ca). Always we can use this formula or any other restriction is there. Can you explain me?
Khan said:
1 decade ago
A's 1 day work is 1/16.
B's 1 day work is 1/12. As given.
That means C's 5 days work is 5/48 na?
B's 1 day work is 1/12. As given.
That means C's 5 days work is 5/48 na?
Shakti said:
1 decade ago
Let total work = 48.
Then A effi. = 3, b = 4 and find C effi. as (7+n)*4 = 48.
It comes 5.
Hence divide 48 by 5 and get your answer.
Then A effi. = 3, b = 4 and find C effi. as (7+n)*4 = 48.
It comes 5.
Hence divide 48 by 5 and get your answer.
Sagar Malunjkar said:
1 decade ago
@Surendra.
See carefully,
In second last step we have calculated C's 1days work is 5/48.
But our exact question is "C alone can do the job in how much days" so according to formula -
If C's 1 day's work = 1/n, then C can finish the work in n days ie n/1 days.
So that's why 5/48 became 48/5.
See carefully,
In second last step we have calculated C's 1days work is 5/48.
But our exact question is "C alone can do the job in how much days" so according to formula -
If C's 1 day's work = 1/n, then C can finish the work in n days ie n/1 days.
So that's why 5/48 became 48/5.
Surendra said:
1 decade ago
Why you have shown 48/5 instead of 5/48?
Jeevi said:
1 decade ago
The 5 is base and 5 table 9*5=45 remain 3 so you should write 9 3/5 are you understand.
Chethan k m said:
1 decade ago
How to write 48/5 in the form of 9 3/5?
Hasan Ali Tariq said:
1 decade ago
@Carlo.
I think Carlo explain it nicely and simply. The issue of inverse value 5/48 to 48/5.
I think Carlo explain it nicely and simply. The issue of inverse value 5/48 to 48/5.
Dumapti Mahesh said:
1 decade ago
I have another method to solve this:
Suppose the C's work take as z days.
We have the formula that (A+B+C) work = (xyz/(xy+yz+zx)).
Here x=12(A alone work),y=16(B alone work).
=>192z/(192+16z+12z)=4 days(given).
upon simplifying. we get,
48z = 192+28z.
z = 192/20=> 48/5.
Suppose the C's work take as z days.
We have the formula that (A+B+C) work = (xyz/(xy+yz+zx)).
Here x=12(A alone work),y=16(B alone work).
=>192z/(192+16z+12z)=4 days(given).
upon simplifying. we get,
48z = 192+28z.
z = 192/20=> 48/5.
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