Question

22. If a sum of money at simple interest doubles in 12 years, the rate of interest per annum is:
(a) 16.66% 68.33% (c) 7.5% (d) 10%
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Answer 1

Answer:

SI = P.R.T

2 = 1.R.12

R =1/6 .100

R = 16.66 %

Step-by-step explanation:

interest is doubled

SI=2

Answer 2

The rate of interest per annum is 8.33%

Step-by-step explanation:

Let principal be x

We are given that a sum of money at simple interest doubles in 12 years

So, Amount = 2x

Simple interest = Amount - Principal = 2x-x = x

Time = 12 years

$Si =\frac{P \times T \times R}{100}\\x = \frac{x \times 12 \times R}{100}\\\frac{100}{12}=R\\8.33\%=R$

Hence the rate of interest per annum is 8.33%

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