A certain sum of money at simple interest amounts to Rs.1020 in 2(1/2) years and to Rs. 1067.20 in 4 years. The rate of interest per annum is:

2.5%

3%

4%

5%

Correct Answer : C

In a sale, a perfume is available at a discount of 15% on the selling price. If the perfume’s discounted selling price is Rs.3675.40, what was the original selling price of the perfume?