Question

The population of a variety of tiny bush in an experimental field increased by 10% in the first year, increased by 8% in the second year but decreased by 10% in the third year. If the present number of bushes in the experimental field is 26730 then find the sum of digits of number of bushes in the beginning.

Answer 1

Let the number of bushes in the beginning is P so
$P\times (1+\frac{10}{100})(1+\frac{8}{100})(1-\frac{10}{100})=26730$
$\Rightarrow P=\frac{26730}{(1+\frac{10}{100})(1+\frac{8}{100})(1-\frac{10}{100})}$
$\Rightarrow P=(26730\times \frac{10}{11}\times \frac{25}{27}\times \frac{10}{9})$
$\Rightarrow$ P = 25000