Question

In a simple interest. at what rate percent per annum will a sum of money double in 8 years?

• A. $12.5\%$
• B. $10.5\%$
• C. $12.0\%$
  
• D. $15.5\%$
  

Answer 1

Answer: (A)

$12.5\%$

Let the initial sum of money be $P$.

Let time in years be $t$ and rate be $r$.

$Finalsum=2\times P$

$Simpleinterest=\frac{P\times t\times r}{100}$

$Totalsum=P+\frac{P\times t\times r}{100}$

$2P=P+\frac{P\times t\times r}{100}$

$P=\frac{P\times t\times r}{100}$

given time = 8 years

$r=100/8=12.5\%$