Question

At what rate of interest per annum $SI$ will a sum of money triple in $20$ years?

Answer 1

Let $T=20years$. According to the question,

$Amount=3\left(Principle\right)$

$A=3P$

$S.I.=A-P$

$=3P-P$

$=2P$

$S.I.=\frac{P\times R\times T}{100}$

$2P=\frac{P\times R\times 20}{100}$

$R=\frac{2P\times 100}{P\times 20}$

$R=10\%$