Question

How many kg of pure salt must be added to $30$kg of $2\%$ solution of salt and water to increase it to a $10\%$ solution?

Answer 1

Given : $2\%$ salt must be added to $30$ kg solution

Then amount of salt in 30 kg solution $=\frac{2}{100}\times 30=0.6$ kg

Let $x$ kg of pure salt added

$\therefore \frac{0.6+x}{30+x}=\frac{10}{100}$

$\Rightarrow 60+100x=300+10x$

$\Rightarrow 100x-10x=300-60$

$\Rightarrow 90x=240$

$\Rightarrow x=\frac{240}{90}=\frac{8}{3}$

Then $\frac{8}{3}=2\frac{2}{3}$ kg salt added in solution