Question

How many kg of pure salt must be added to 30kg of 2% solution of salt and water to increase it to a10% solution ?

Answer 1

Solution:

Amount of salt in 30 Kg solution = $(\frac{2}{100}\times 30)$ kg = 0.6 kg.
Let x kg of salt be added.

Then, $\left(\frac{0.6+x}{30+x}\right)=\frac{10}{100}$
60+100x = 300+10x
x = $\frac{240}{90}=\frac{8}{3}$ = 2.6 kg

So we need to add 2.6 kg of pure salt in 30 kg of 2% solution of salt and water to increase it to a 10% solution.