Question

How many quarts of pure antifreeze must be added to 9 quarts of a 10​% antifreeze solution to obtain a 30​% antifreeze​ solution?

Answer 1

Answer: 2.6 quarts

Explanation:

According to ratio and proportion:

where,

$C_1$ = concentration of first solution = 10 %

$m_1$ = mass of first solution = 9 quarts

$C_2$ = concentration of pure solution = 100%

$m_2$ = mass of pure solution = x quarts

$C_3$ = concentration of final solution = 30 %

$m_3$ = mass of final solution = (9+x) quarts

$10\times 9+100\times x=30\times (9+x)$

$x=2.6quarts$

Thus 2.6 quarts must be added to 9 quarts of a 10​% antifreeze solution to obtain a 30​% antifreeze​ solution.