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 2 of 23.
Shivaji 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.
(56)
Rahul Kapoor said:
2 years ago
A work done in 16 days.
B work done in 12 days.
A, B and C work done 4 days.
Total work 16,12,4.
Total work 48.
Efficiency of A 48/16 = 3
Efficiency of B 48/13 = 4
Efficiency of A+B+C = 48/4 = 12.
Efficiency of C = 12 - 4 - 3 = 5.
C completed the work alone =48/5.
B work done in 12 days.
A, B and C work done 4 days.
Total work 16,12,4.
Total work 48.
Efficiency of A 48/16 = 3
Efficiency of B 48/13 = 4
Efficiency of A+B+C = 48/4 = 12.
Efficiency of C = 12 - 4 - 3 = 5.
C completed the work alone =48/5.
(105)
RAMAKRISHNA MACHARLA said:
3 years ago
A = 1/16.
B = 1/12.
A+B+C = 1/4.
1/16 + 1/12 + C = 1/4
C = 1/4 - 1/16 - 1/12
C = 5/48 = 48/5.
C = 9 * 3/5.
B = 1/12.
A+B+C = 1/4.
1/16 + 1/12 + C = 1/4
C = 1/4 - 1/16 - 1/12
C = 5/48 = 48/5.
C = 9 * 3/5.
(99)
Ion Strait said:
3 years ago
The reason that 5/48 becomes 48/5 is that C's one day work = 5/48.
Here it means, the total work in units is 48 and out of that C does 5 units of work in 1 day, so it's 5/48.
But the question asks the time required for C alone to complete the work.
Since, 48 units are the total work, just divide it by the one-day unit of C's work, that is, 5
So, 48/5.
Here it means, the total work in units is 48 and out of that C does 5 units of work in 1 day, so it's 5/48.
But the question asks the time required for C alone to complete the work.
Since, 48 units are the total work, just divide it by the one-day unit of C's work, that is, 5
So, 48/5.
(51)
Tarun kumar agrawal said:
3 years ago
Given that;
A complete the work in --> 16 days.
B complete the work in --> 12 days.
With the help of C (A+B+C) complete the work in --> 4 days.
We take LCM OF (16,12,4) comes --> 48 unit.
A complete --> 48/16 = 3 unit per day.
B complete --> 48/12 = 4 unit per day.
A+B+C complete --> 48/4 = 12 unit per day.
C alone do --> 12-3-4 = 5 unit per day.
so C take time to complete the work in days = total unit/unit per day by c.
= 48/5.
= 9(3/5) days.
When we divided 48 by 5 quotient comes to 9 and the remainder is 3 . it is a mixed fraction.
A complete the work in --> 16 days.
B complete the work in --> 12 days.
With the help of C (A+B+C) complete the work in --> 4 days.
We take LCM OF (16,12,4) comes --> 48 unit.
A complete --> 48/16 = 3 unit per day.
B complete --> 48/12 = 4 unit per day.
A+B+C complete --> 48/4 = 12 unit per day.
C alone do --> 12-3-4 = 5 unit per day.
so C take time to complete the work in days = total unit/unit per day by c.
= 48/5.
= 9(3/5) days.
When we divided 48 by 5 quotient comes to 9 and the remainder is 3 . it is a mixed fraction.
(122)
SHAILESH SALVE said:
3 years ago
How 5/48 to 48/5? Please explain this step.
(24)
A SANTHI said:
3 years ago
A - 16 Days.
B - 12 days.
A + B + C - 4 days.
We know A and B's one day work - 1/16 and 1/12.
Therefore, Add A+B = 1/16+1/12 (Take LCM).
= 7/48( Which is the one day work for A+B).
We know A+B+C's one-day work = 1/4.
So, A+B+C= 1/4,
7/48+C= 1/4, ( A+B= 7/48 )
C= 1/4 - 7/48 (Take LCM).
C= 5/48 (One day work).
Therefore C's Work = 48/5 (Just inverse of one day),
C= 9 * 3/5.
B - 12 days.
A + B + C - 4 days.
We know A and B's one day work - 1/16 and 1/12.
Therefore, Add A+B = 1/16+1/12 (Take LCM).
= 7/48( Which is the one day work for A+B).
We know A+B+C's one-day work = 1/4.
So, A+B+C= 1/4,
7/48+C= 1/4, ( A+B= 7/48 )
C= 1/4 - 7/48 (Take LCM).
C= 5/48 (One day work).
Therefore C's Work = 48/5 (Just inverse of one day),
C= 9 * 3/5.
(20)
Rickykerketta said:
3 years ago
A --- 15.
B --- 20.
We took LCM -- 60.
15 * 4 = 60.
20 * 3 = 60.
Work done = 4 days * 7 = 28 units of work.
60 - 28 = 32,
Part left = 32/60,
8/32.
B --- 20.
We took LCM -- 60.
15 * 4 = 60.
20 * 3 = 60.
Work done = 4 days * 7 = 28 units of work.
60 - 28 = 32,
Part left = 32/60,
8/32.
(5)
Vaishnavi Deshpande said:
3 years ago
Why do not we consider work done by A+B in 4 days and then subtract it from 1 to get work done by C in 4 days? Please anyone explain me.
(2)
Dibyanshu said:
3 years ago
@Nil.
It's a fractional rule.
48/5 = 9+3/5.
Let me explain.
=> 5x9 = 45
So, you can say the reminder a numerator and the denominator is also a denominator.
The reminder is 3 and the Denominator is 5.
So, 9*3/5..
It's a fractional rule.
48/5 = 9+3/5.
Let me explain.
=> 5x9 = 45
So, you can say the reminder a numerator and the denominator is also a denominator.
The reminder is 3 and the Denominator is 5.
So, 9*3/5..
(6)
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers