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Aptitude - Time and Work - Discussion

Discussion Forum : Time and Work - General Questions (Q.No. 23)
Time and Work
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?
18 days
24 days
30 days
36 days
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 2 of 7.
Aditya said:   1 decade ago
Why we added 2 in the beginning?
(1)
AKSHAY said:   7 years ago
Thanks for the answer @Nikhil.
(1)
Vamsintr said:   1 decade ago
A+B+C=1/16, B+C=1/24.

(A+B+C) - (B+C) =1/16-1/24.

By solving we get 1/48.
(1)
Tanvir said:   5 years ago
How you got A's 1 day work?
(1)
Archana said:   5 years ago
@Nikhil.

Veery good explanation. Thanks.
(1)
Dharmendra kushwaha said:   9 years ago
@Suji.

Your explanation clears my doubt, Thank you.
Gobind Mandal said:   9 years ago
Can anyone please explain m,e that how did you multiply by 48?

3/8 * 48?
Rahul R said:   9 years ago
Thanks, @Nikhil. It's very useful to me.
Shanmugam said:   9 years ago
2( A+B+C) = 15 units.
A+B+C = 7.5 units.

I can't understand this equation @Nikhil.
Lavanya said:   9 years ago
I am not understanding how they work 10 days?

Please explain it.
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