Rupees 10,000 is invested at 6% interest compounded annually. How long will it take to accumulate Rs. 20, 000 in the account?

Rupees 10,000 is invested at 6% interest compounded annually. How long

1.	Rupees 10,000 is invested at 6% interest compounded annually. How long will it take to accumulate Rs. 20, 000 in the account?
Answer» Correct Answer - 12 years Principal amount = Rs. 10,000 Rate of interest = 6% So, amount after one year = Rs. `1.06 xx 1000` Amount after two years = Rs. ` 1.06 xx 1.06 xx 10000` Rs.` (1.06)^(2) xx 10000` and so on So, amount accumulated after n years = Rs. `(1.06)^(n) xx 10000`. Now,` (1.06)^(n) xx 10000 = 20000` ` :. (1.06)^(n) = 2` ` rArr n log_(10)1.06 = log_(10) 2` ` rArr n = (log_(10)2)/(log_(10)1.06) = (0.30103)/(0.025306)` ` rArr log n = log 0.30103 - log 0.025306` ` =-0.5213 - (-1.5968)` ` = 1.0755` ` =11.89` So, it will take approximately 12 years.