Question

a can do a certain work in 14 days while B can do it in 21 days. they work together for 7 days.then a fell and B have to complete the remaining work. in how many days was the work completed?

Answer 1

A’s one day work =1/14

B’s one day work=1/21

(A+B)’s one day work =1/14+1/21=(3+2)/42 =5/42

(A+B) can do the work in =42/5 =8.4 days

They work together in =(8.4–3)= 5.4days

Work done by both in 5.4 days =(5/42)×5.4

=5×54/42×10= 9/7×2= 9/14 work.

Remaining work =1- 9/14=5/14.

1 work B can do in = 21 days

5/14 work B can do in =21×5/14 =15/2=7.5 days

Total days to complete the work=5.4+7.5

=12.9 days or 13 days. Answer.

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