The C.I. on a certain sum of money for the 4th year at 8% p.a. is Rs. 486. What was the compound interest for the third year on the same sum at the same rate?
1). Rs. 450
2). Rs. 475
3). Rs. 456
4). None of these
Let the basic amount for the 4th year be ‘x’
∴ According to the first given condition,
⇒ 486 = x × (1 + 0.08) - x
∴ 0.08x = 486
∴ x = 6075
∴ Amount after 3rd year = 6075
Let the base amount for the 3rd year be ‘y’
∴ 6075 = y × (1 + 0.08)
∴ y = 5625
∴ C.I for the 3rd year = 6075 - 5625 = 450
∴ The Compound Interest for the 3rd year is Rs. 4507. At what rate percent per annum will a sum of money double in 8 years.