Question

the simple interest on a sum of money is 4 by 9 of the principal and the number of years is equal to the rate percent per annum what is the rate percent per annum

Answer 1

$let \: p = x \\ si = \frac{4}{9} x \\ t = r \\ si = \frac{prt}{100} \\ \frac{4}{9} x = \frac{x \times r \times r}{100} \\ {r}^{2} = \frac{4 \times 100}{9} \\ r = \frac{2 \times 10}{3} = \frac{20}{3} = 6 \frac{2}{3}\%$