Question

When the price of TV set was increased by $30\%$, then number of TV sets sold decreased by $20\%$. What was the effect on the sales?

• A. $5\%$ decrease
• B. $7\%$ increase
• C. $6\%$ decrease
• D. $4\%$ increase

Answer 1

The correct option is D $4\%$ increase

Let initial price by $x$ & TV sold $=y$
Change in sale $=$ $(1.3\times x)\left(0.8y\right)-xy$
$\therefore$ change in sale $=1.04xy-xy=0.04xy$
Percent increase/decrease $=[\frac{0.04xy}{xy}\times 100]=4\%$ increase.