Aptitude - Time and Work - Discussion
Discussion Forum : Time and Work - General Questions (Q.No. 23)
23.
A and B can do a piece of work in 30 days, while B and C can do the same work in 24 days and C and A in 20 days. They all work together for 10 days when B and C leave. How many days more will A take to finish the work?
Answer: Option
Explanation:
| 2(A + B + C)'s 1 day's work = |  |
1 | + | 1 | + | 1 |  |
= | 15 | = | 1 | . |
| 30 | 24 | 20 | 120 | 8 |
| Therefore, (A + B + C)'s 1 day's work = | 1 | = | 1 | . |
| 2 x 8 | 16 |
| Work done by A, B, C in 10 days = | 10 | = | 5 | . |
| 16 | 8 |
| Remaining work = | |
1 - | 5 | |
= | 3 | . |
| 8 | 8 |
| A's 1 day's work = | |
1 | - | 1 | |
= | 1 | . |
| 16 | 24 | 48 |
| Now, | 1 | work is done by A in 1 day. |
| 48 |
| So, | 3 | work will be done by A in | |
48 x | 3 | |
= 18 days. |
| 8 | 8 |
Discussion:
61 comments Page 4 of 7.
Sanjiv said:
9 years ago
Why not like this?
x + 10/48 + 10/80 + 10/60 = 1
Then, we get x = 24 days.
Plese reply for me.
x + 10/48 + 10/80 + 10/60 = 1
Then, we get x = 24 days.
Plese reply for me.
Pari said:
10 years ago
Why we take 1/24, from where its comes?
Pooja said:
10 years ago
How to add fractions like the above one in the questions? I am not getting 15/120 please explain.
Pooja said:
10 years ago
How to solve fractions like 1/30+ 1/24+1/20? Please someone explain in details I am not getting 15/120 as answer please.
Sajal said:
10 years ago
I want to ask that why we have solved the equations at the top?
Bikash Choudhury said:
1 decade ago
LCM of 30, 24, 20 is 120.
A+B B+C C+A A+B+C.
4 5 6 2 (a+b+c) = 15.
=> a+b+c = 15/2.
A+B+C do for 10 means they work together 10*15/2 = 75 units of work.
Work remains 120-75 = 45 unit.
A 's one day work = (A+B+C)-(B+C) = 15/2-5 = 5/2.
Hence A can finish the remaining work = 45*2/5 = 18.
A+B B+C C+A A+B+C.
4 5 6 2 (a+b+c) = 15.
=> a+b+c = 15/2.
A+B+C do for 10 means they work together 10*15/2 = 75 units of work.
Work remains 120-75 = 45 unit.
A 's one day work = (A+B+C)-(B+C) = 15/2-5 = 5/2.
Hence A can finish the remaining work = 45*2/5 = 18.
(3)
Sikandar said:
1 decade ago
As 1 day work = (A+B+C)-(B+C).
= 1/16-1/24 = 1/48.
= 1/16-1/24 = 1/48.
(1)
Varsha said:
1 decade ago
How did you calculated A's work for 1 day when we do not know any individual work for 1 day?
Hanumant said:
1 decade ago
I am not understanding how to calculate 1/48.7/240.1/80?
Shail said:
1 decade ago
@Aditya.
Because a+b.
b+c.
c+a.
So we take out common 2 in the beginning. Got it dear.
Because a+b.
b+c.
c+a.
So we take out common 2 in the beginning. Got it dear.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers