Question

A can finish the work in 16 days while B can finish the work in 8 days. After A started the work alone, B joined him after 4 days. Find out the total time taken to finish the work.

• A. 4 days
• B. 8 days
• C. 6 days
• D. 14 days
• E. 16 days

Answer 1

The correct option is B 8 days

A can finish the work in 16 days. In one day he can finish % of the work.

In 4 days, working alone he will finish = 25% of the work.

Now B joins him.

Amount of work left = 100 – 25 = 75%.

B can do % of the work.

A and B together can do % + % = % of the work.

Work left = 75%. Hence time taken = = 4 days.

So, total time taken = 4 + 4 = 8 days. Option (2).

2nd method:- In 4 days A will finish 25% of work. Remaining work is 75%, Efficiency of B is double than A i.e 50% work will do by B and 25% will do by A. Thus it will take 4 days . Total 8 days. Option (2).