Question

68. The simple interest on a sum of money is Rs.144/-. If rate per cent of the interest per annum
equals the number of years, the rate per cent per annum is:​

Answer 1

Answer:

$Let \: the \: principal \: be \: P$

$Rate \: of \: interest \: be \: R \: \%$

$According \: to \: the \: question, Time = R$

$Simple \: interest = \frac{4P}{9}$

$SI = \frac{(PTR)}{100}$

$⇒ \frac{4P}{9} = \frac{(PTR)}{100}$

$⇒ \frac{4P}{9} = \frac{(P \times R \times R)}{100}$

$⇒ \frac{4P}{9} = \frac{(P \times R²)}{100}$

$⇒R² = 100 \times \frac{4}{9}$

$⇒R=10 \times \frac{2}{3} = \frac{20}{3}$

$Therefore, \: rate \: of \: interest \: is \:$

$\frac{20}{3} \% \: or \: 6 \frac{2}{3} \%.$