Q10---------------A can do a piece of work in 20 days .He works at it 5 days a,...............?

Question

Q10---------------A can do a piece of work in 20 days .He works at it 5 days and then B finishes it in 10 more days.With the help of C,they finish it in 2 days.How much should C be paid for his contribution.
a.8 days
b. 10 days
c. 12 days
d. 6 days

Answer 1

All the questions you're posting are worded pretty strangely. Are you translating from another language into English?

Anyway, A can do the work in 20 days, so he does 1/20 of the task per day. If he works five days, he does 1/4 of it.

If B takes 10 more days to finish, B can do 3/4 of the task in 10 days, so he does 3/40 of the task per day.

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From this point, the question is unclear.

(a) If you mean that A+B+C work together and all complete the task from the start, in two days, then:

In two days, A would do 2*(1/20), or 1/10 of the task, and B would do 2*(3/40) or 3/20 of the task. Together that is: 1/10 + 3/20 = 2/20 + 3/20 = 5/20 = 1/4.

In the same two days, C must be doing 3/4 of the task if it is finished at the end of two days. That is the equivalent of 10 days of B's work (3/40 * 10 = 3/4) -- or 15 days of A's work.

(b) If you mean that B+C together finish in 2 days the part that used to take B 10 days, then C does the remaining 8 days of B's work in those 2 days -- the equivalent of 12 days of A's work.

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There are two things that aren't clear:

(a) What the "two days" refers to,
(b) Whose "days" C is paid in.

A and B work at different rates (B is 1.5 times as fast as A, since he finishes the task in 10 days when it would have taken A 15 days), so it's really odd to ask how may "days" C should be paid for. If you compute the number of days of A's work he saves, it's a different number than if you compute the number of days of B's work that he saves.

Answer 2

A does 1/20 of the work in 1 day. B does 3/4 of the work in 10 days. A,B,C together do 3/4 of the work in 2 days.

A = 1/20
B = 3/40
A+B+C = 3/8
C = 3/8 - 1/20 - 3/40
C = 1/4

In the last two days, C does (1/4)/(3/8) = 2/3 of the work. So 2/3 of the 3/4 of the remaining is 1/2. C does 1/2 of the overall work. I'm uncertain about what he should get paid for this, maybe 10 days worth? Since A takes 20 days to finish the whole thing?

Answer 3

Q10) Working alone.A can do the work in 20 days.
Hence,in 1 day,he does 1/20 part of the work and in 5 days he finishes 5/20 or 1/4th part of the work
Remainig work=1-1/4=3/4 part
B finishes 3/4 part of the work in 10 days
Hence in 1 day ,he does3/40 part of the work
A+B+C ,working together completes the work in 2 days
Theefore,in 1 day,they do 1/2 of the work working together
But A+B in 1 day do 1/20 +3/40 or 5/40 part of the work
Henve C can do (1/2 -5/40) or 15/40 part of the work in 1 day,working alone
hence the share of contribution for the work of A,B and C is
1/20:3/40:15:40
=2:3:15
In perecentage it is 15*100/20 =75%
But sadly in the option of answers there is no answer which points to the payment.hence,the answer should technically be "None of the above"