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 19 of 23.
Anup said:
6 years ago
16,12,4 of lcm=48.
16/48=3.
12/28=4.
4/48=12.
So, total works efficiency =12-7=5 per days;
48/5 is the answer.
16/48=3.
12/28=4.
4/48=12.
So, total works efficiency =12-7=5 per days;
48/5 is the answer.
Neha k. said:
6 years ago
I can't understand 9 3/5 last answer.
Vignesh said:
5 years ago
@Neha.
It is 48/5=> 45+3/5 = 9 * 3/5.
It is 48/5=> 45+3/5 = 9 * 3/5.
Sonu singh said:
5 years ago
Thanks all for explaining.
Billal Hossain said:
5 years ago
Solution:
Let, C did the job in= x days.
ATQ,
1/16+ 1/12+ 1/x = 1/4.
=> 1/x= 1/4- 1/16-1/12,
=> 1/x= (12-3-4)/48,
=> 1/x= 5/48,
=> x= 48/5,
=> x = 9 (3/5).
C alone can do the job in 9(3/5) days.
Let, C did the job in= x days.
ATQ,
1/16+ 1/12+ 1/x = 1/4.
=> 1/x= 1/4- 1/16-1/12,
=> 1/x= (12-3-4)/48,
=> 1/x= 5/48,
=> x= 48/5,
=> x = 9 (3/5).
C alone can do the job in 9(3/5) days.
Cherry said:
5 years ago
Good explanation, Thanks @Billal Hossain.
Chaitanya Galande said:
5 years ago
Consider A and B work alone.
1/16 + 1/12.
3/48 and 4/48.
That means A does work 3 units per day and B does 4 units per day.
So, now total work is done by A and B in one-day => 4 + 3 = 7 units per day
The total work is done by A and B in 4 days = 28 units.
Remaining units = 48-28 = 20 units.
That means 20 units work is done by C in 4 days in order to complete the work;
So, WORK DONE BY C IN ONE DAY = 20/4= 5 UNIT PER DAY,
C alone can do work in = 48/5 i.e 9(3/5).
1/16 + 1/12.
3/48 and 4/48.
That means A does work 3 units per day and B does 4 units per day.
So, now total work is done by A and B in one-day => 4 + 3 = 7 units per day
The total work is done by A and B in 4 days = 28 units.
Remaining units = 48-28 = 20 units.
That means 20 units work is done by C in 4 days in order to complete the work;
So, WORK DONE BY C IN ONE DAY = 20/4= 5 UNIT PER DAY,
C alone can do work in = 48/5 i.e 9(3/5).
Sana said:
5 years ago
Why the fraction is reciprocated at the end? Explain me, please.
Ishwar said:
5 years ago
Because time is inversely proportional to Rate and your calculated rate is 5/48 (this is C`s rate at which C working so).
(1)
Jeet said:
5 years ago
Take LCM of A and B.
The total work is 48.
A + B = 7 what should we add here so that work would complete in 4 days! So that number is 5.
3+4+5=12.
You can see they all can complete 48 works in 4 days. (48/12=4).
Therefore C's capacity is 5. When you'll divide the work by 5.
48/5 you'll get 9 3/5.
The total work is 48.
A + B = 7 what should we add here so that work would complete in 4 days! So that number is 5.
3+4+5=12.
You can see they all can complete 48 works in 4 days. (48/12=4).
Therefore C's capacity is 5. When you'll divide the work by 5.
48/5 you'll get 9 3/5.
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