Question

4. A can do a piece of work in 20 days while B can do it in 15 days. With the help of C, they finish
the work in 5 days. In what time would C alone do it?
5. A can do a piece of work in 12 days and B alone can do it in 16 days. They worked together on i
for 3 days and then A left. How long did B take to finish the remaining work?​

Answer 1

Step-by-step explanation:

For Question 4 :-

A do it in 20 days. that means in one day it will do in - 1/20 days.

Similarly for B is 1 / 15 for one day work.

Total Work with C is 5 days. ( For one day it is 1/5 )

So Work done by C is

A + B + C = 1 / 5

C = 1 / 5 - ( 1 / 15 + 1/ 20 ) = 1 / 12.

So C will Finish it in 12 days.

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For Question 5.

A do it in 12 days.

B do it in 16 days.

Total Work is done in 48 days.

Efficiency of A is 48 / 12 = 4

Efficiency of B is 48 / 16 = 3.

So In total work is done by a and b in one day

4 + 3 ---------48 days.

7 ---------------48. days.

Here they initially work both for 3 days ie

7 * 3 = 21 days. they work both but After it B left that means Remaining Work is ( 48 - 21 = 27 ) days which will be done by B.

and we know that time = work / Efficiency

days = 27 / 3 = 9 days Ans

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