Q12 of 52 Page 112

Let us write by calculating the sum of money, if the difference between compound interest and simple interest for 2 years at the rate of 9% interest per annum is ₹129.60.

Let principal = ₹x


∴ Simple interest at 9% for 2 years



= ₹0.18x


At the rate of 9% compound interest per the annum the amount for 2 years



= ₹1.1881x


∴ Compound interest for 2 years = ₹1.18x – x = 0.1881x


By the condition, 0.1881x – 0.18x = 129.60


⇒ 0.0081x = 129.60


∴ x = ₹16000


∴ Principal is ₹16000


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