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 22 of 23.
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.
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.
Sai said:
5 years ago
Answer is 9 3/5 days.
Karthick said:
5 years ago
How did come 5/48? Explain please.
Palem Ganesh said:
5 years ago
It's quite easy, I will tell the shortcut method.
Take LCM of 16 an 12 is 48 and;
Then find one day work as units.
A = 48/16 = 4.
B = 48/12 = 3.
C = ?.
We know they all together they take just 4 days.
Per day of 4 days work = 48/4 = 12.
A + B + C = 12.
4 + 3 + C = 12.
C = 5.
So, C can do work 5 units per day.
C= 48/5.
Take LCM of 16 an 12 is 48 and;
Then find one day work as units.
A = 48/16 = 4.
B = 48/12 = 3.
C = ?.
We know they all together they take just 4 days.
Per day of 4 days work = 48/4 = 12.
A + B + C = 12.
4 + 3 + C = 12.
C = 5.
So, C can do work 5 units per day.
C= 48/5.
Jaya said:
5 years ago
Thank you friends.
Disha said:
4 years ago
5/48 of the whole work is done in one day. Then one whole work is;
5/48:1::1:x.
1*1/[5/48] = 48/5.
5/48:1::1:x.
1*1/[5/48] = 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.
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