Question

13) If one invests Rs. 10,000 in a bank at a rate of
interest 8% per annum, how long does it take
to double the money by compound interest?
[(1.08)^5 = 1.47]

Answer 1

Answer:

9 years

Step-by-step explanation:

In this question,

We have been given that,

If one invests Rs. 10,000 in a bank at a rate of Interest 8% per annum,We need to find how long does it take to double the money by compound Interest?

Here Principle = Rs.10,000

        Rate of Interest = 8%

       Amount = Rs 20,000

Formula for the compound Interest is given by

Amount  = Principle(1 + $\frac{rate}{100})^{time}$

Putting the values we get,

20000 = 10000(1 + $\frac{8}{100})^{time}$

2 = $(1.08)^{time}$

$(1.08)^{9}\ =\ (1.08)^{time}$            Taking $(1.08)^{9}\ =\ 2$

Comparing the exponential powers we get,

Time = 9 years

Time taken to double the Money will be 9 years.  

Answer 2

Step-by-step explanation:

Step-by-step explanation:

Amount invested = Rs. 10000

Interest rate = `8/100` = 0.08

amount after 1  year = 10000 (1 + 0.08)

= 10000 (1.08)

Value of the amount after n years

= 10000 (1.08)^n

= 20000

∴ (1.08)^n  = 2

(1.08)^5  = 1.47     ...[Given]

∴ n = 10 year. (approximately)

This is 100% correct answer