Question

A quantity of $30$ ml of $20\%$ alcohol is mixed with $20$ ml of $25\%$ alcohol What is the strength of alcohol in the mixture?

• A. $20\%$
• B. $27\%$
• C. $30\%$
• D. $22\%$

Answer 1

The correct option is D $22\%$

Quantity of alcohol in $30$ ml solution $=20\%$ of $30$ ml $=6$ ml
Quantity of alcohol in $20$ ml solution $=25\%$ of $20$ ml $=5$ ml
$\therefore$ Percentage of alcohol in the mixture $=$ $\frac{6+5}{(30+20)}\times 100=\frac{11}{50}\times 100=22$ $\%$