A) 7 yr
B) 2 yr
C) 15 yr
D) None of these
Correct Answer: B
Solution :
Suppose interest rate = r% per annum and principal amount = Rs. x Then, by question, \[x{{\left( x+\frac{r}{100} \right)}^{4}}=2\] After cubing both sides, we have \[{{\left[ x\left( x+\frac{r}{100} \right) \right]}^{12}}={{2}^{3}}\] So, \[{{\left[ x\left( x+\frac{r}{100} \right) \right]}^{12}}=8\]times Therefore, the required time = 12 yrYou need to login to perform this action.
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