Advertisement

### Question

A can do a piece of work in 39 days. B is 30% more efficient than A. In how many days will they complete the work if they work together?

**A**

$16{22/23}$ days.

**B**

17 days.

**C**

$17{1/23}$ days.

**D**

$17{2/23}$ days.

**Soln.**

**Ans: a**

Let us first calculate the one day work of B. One day work of A is given as $1/39$. If B is 30% efficient, then one day work of B is $1/39$ × $130/100$ = $1/30$. Putting x = 39 and y = 30 in the shortcut method, we get ${xy}/{x + y}$ = ${390/23}$, which is same as: $16{22/23}$.