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 3 of 23.
Dibyanshu said:
3 years ago
The work is completed by A in 16 days and by B in 12.
LCM of 16 and 12 is 48.(Total work is also 48).
The efficiency of A= 48/16=3 and B= 48/12=4,
They complete the work in 4 days.
Total work/time = Efficiency.
48/4 = 12(Efficiency of A+B+C = 12).
The efficiency of A+B is 3+4=7
The efficiency of C is 12 - 7 = 5.
Total work/Efficiency = Time.
48/5 = 9.6 is also written as (9*3/5).
LCM of 16 and 12 is 48.(Total work is also 48).
The efficiency of A= 48/16=3 and B= 48/12=4,
They complete the work in 4 days.
Total work/time = Efficiency.
48/4 = 12(Efficiency of A+B+C = 12).
The efficiency of A+B is 3+4=7
The efficiency of C is 12 - 7 = 5.
Total work/Efficiency = Time.
48/5 = 9.6 is also written as (9*3/5).
(10)
Nil said:
3 years ago
How 48/5 is written as 9*3/5? Please explain.
(1)
Deekshit said:
4 years ago
Why the fraction 5/48 is changed to 48/5? Please explain.
Teja said:
4 years ago
A = 16
B = 12.
A + B + C = 4.
16,12,4 LCM = 48.
then,16/48 = 3.
12/48 = 4.
4/48 = 12.
Then,C - (A + B) = 12-(3+4) = 5.
then 48/5.
B = 12.
A + B + C = 4.
16,12,4 LCM = 48.
then,16/48 = 3.
12/48 = 4.
4/48 = 12.
Then,C - (A + B) = 12-(3+4) = 5.
then 48/5.
(5)
Sangmesh said:
4 years ago
5/48 how this came? Please explain.
(1)
Harshal said:
4 years ago
First A=12.
and B=20.
Now the lcm of A and B is 60.
than A and B one day work is 7 and he's work together 7*4=28.
now the 28/60 forestation is 7*15.
and renaming work - total work 28-60=32.
Now 32/60= forestation us 8/15 answer.
and B=20.
Now the lcm of A and B is 60.
than A and B one day work is 7 and he's work together 7*4=28.
now the 28/60 forestation is 7*15.
and renaming work - total work 28-60=32.
Now 32/60= forestation us 8/15 answer.
Talib said:
4 years ago
A = 16.
B = 12.
A + B + C = 4.
Total work by a, b, c ie LCM of 16, 12, 4 = 48.
Then A work in 1 day = 48/16 = 3unit.
and B work in 1 day = 48/12 = 4 unit.
And A +B+C work in 1 days = 48/4= 12 unit.
Therefore put value of a and b ie 3 + 4 + c = 12.
ie c work in 1 day = 5 unit.
Therefore total work done by C is 48/5 ans simple and fast method.
B = 12.
A + B + C = 4.
Total work by a, b, c ie LCM of 16, 12, 4 = 48.
Then A work in 1 day = 48/16 = 3unit.
and B work in 1 day = 48/12 = 4 unit.
And A +B+C work in 1 days = 48/4= 12 unit.
Therefore put value of a and b ie 3 + 4 + c = 12.
ie c work in 1 day = 5 unit.
Therefore total work done by C is 48/5 ans simple and fast method.
(3)
St_osagie said:
4 years ago
@All.
Those asking this question: How did come 5/48?
It is called the "rule of flip in time and work" which is how efficiency in piece is derived. Eg. If it takes 3 days for tom to perform a given task. Tom's efficiency in piece is 1/3.
Those asking this question: How did come 5/48?
It is called the "rule of flip in time and work" which is how efficiency in piece is derived. Eg. If it takes 3 days for tom to perform a given task. Tom's efficiency in piece is 1/3.
(2)
Nahida Naaz said:
4 years ago
A -> 16
B -> 12.
Lcm -> 48.
Effi 3 and 4.
4 days work of (A+B) :- 4*7 = 28.
Total work - 4 days work of (A+B).
48- 28= 20.
Remaining work of 'C' will do in 4 days
So , 20/4 = 5.
Hence,
Whole work done by 'C'. 48/5.
B -> 12.
Lcm -> 48.
Effi 3 and 4.
4 days work of (A+B) :- 4*7 = 28.
Total work - 4 days work of (A+B).
48- 28= 20.
Remaining work of 'C' will do in 4 days
So , 20/4 = 5.
Hence,
Whole work done by 'C'. 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.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers