Question

A vessel contains pure wine, $10\%$ of wine is drawn and replaced with water. This operation is repeated $3$ times. Calculate the percent of wine drawn from the vessel.

Answer 1

The quantity drawn from the vessel (%)
$=100-100(1-\frac{10}{100})(1-\frac{10}{100})(1-\frac{10}{100})$
$=100-100\times \frac{9}{10}\times \frac{9}{10}\times \frac{9}{10}$
$=100-72.9=27.1$%