1979 AMC 12 Question 15 - thichhoctoan.com

Question 15

Two identical jars are filled with alcohol solutions, the ratio of the volume of alcohol to the volume of water being $p:1$ in one jar and $q:1$ in the other jar. If the entire contents of the two jars are mixed together, the ratio of the volume of alcohol to the volume of water in the mixture is

$\frac{p+q}{2}$
$\frac{p^2+q^2}{p+q}$
$\frac{2pq}{p+q}$
$\frac{2(p^2+pq+q^2)}{3(p+q)}$
$\frac{p+q+2pq}{p+q+2}$