Q. In what time 8000 Rs. will amount to 9261 Rs. at 10% per annum compound interest, when the interest is compounded half yearly?
Answer: 1.5 years
Notes: Interest is compounded half yearly. ∴ Rate of interest = 5% $latex Time = \frac{n}{2}\ years&s=1$ $latex \because A = P(1 + \frac{R}{100})^{T}&s=1$ $latex => 9261 = 8000 (1 + \frac{5}{100})^{n}&s=1$ $latex => \frac{9261}{8000} = (\frac{21}{20})^{n}&s=1$ $latex => (\frac{21}{20})^{3} = (\frac{21}{20})^{n}&s=1$ $latex => n = 3\ half\ years$ $latex = \frac{3}{2}\ years = 1\frac{1}{2}\ years&s=1$ Hence option [A] is correct answer.

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