Question

A can do a work in x days and B can do the same work in y days then the number of days taken by A and B together to complete the work are

• A. $\frac{y}{x+y}$ days
• B. $\frac{x}{x+y}$ days
• C. $\frac{xy}{x+y}$ days
• D. $\frac{xy}{x-y}$ days

Answer 1

Answer: (C)

$\frac{xy}{x+y}$ days

Given A can do work in x days and B can do same work in y days

Then A do work in one day =$\frac{1}{x}$

And B do work in one day =$\frac{1}{y}$

Then A and B do work in one day =$\frac{1}{x}+\frac{1}{y}$

So A and B completed work =$\frac{1}{x}+\frac{1}{y}=\frac{x+y}{xy}$ days