In a certain store, the profit is 320% of the cost. If the cost increases by 25% but the selling price remains constant, approximately what percentage of the selling price is the profit?

Answer: Option B

Let C.P.= Rs. 100. Then, Profit = Rs. 320, S.P. = Rs. 420
New C.P. = 125% of Rs. 100 = Rs. 125
New S.P. = Rs. 420
Profit = Rs. (420 - 125) = Rs. 295
∴ Required percentage
$$\begin{array}{rl}& =\left(\frac{295}{420}\times 100\right)\%\\ & =\frac{1475}{21}\%\\ & =70\%\left(\text{approximately}\right)\end{array}$$