Discussion of Question with ID = 008 under Time-and-Work

This is the discussion forum for this question. If you find any mistakes in the solution, or if you have a better solution, then this is the right place to discuss. A healthy discussion helps all of us, so you are requested to be polite and soft, even if you disagree with the views of others. The question and its current solution has also been given on this page.

Advertisement

Question

A and B can together complete a job in 21 days. A can alone complete it in 28 days. How long would B alone take to finish the job?

A

84 days.

B

85 days.

C

83 days.

D

87 days.

Soln.
Ans: a

One day work of A + B is $1/21$. One day work of A is $1/28$. So one day work of B, say, $1/y$ = $1/21$ - $1/28$. Solving, we get y = 84 days.


Comments and Discussion