In how many months will Rs. 8,000 yield Rs. 2,648 as compound interest at 20% per annum compounded semi-annually?

Let n be number of half years

Amount = 8000 + 2648 = 10648

From the problem statement

10648 = 8000(1 + 0.2/2)ⁿ

1.331 = (1.1)ⁿ

n = 3

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