Vandana bought a watch for ₹ 600 and sold it the same day for ₹ 688.50 at a credit of 9 months and this way she gained 2%. Find the rate of interest per annum.
Correct Answer: 162/3%
Explanation:
SP = 102% of ₹ 600 = (102/100) x 600 = ₹ 612
Now, PW = ₹ 612 and sum = ₹ 688.50
∴ TD = 688.50 - 612 = ₹ 76.50
Thus, SI on ₹ 612 for 9 months is ₹ 76.50.
∴ Rate = (100 x 76.50) / (612 x 3/4)
= (100 x 76.50) / (153 x 3)
=162/3%
