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? (M.A.T., 2004) 2
Answer
Answer (as printed):
Explanation
Amount of salt in 30 kg solution $=\left(\frac{2}{100} \times 30\right) \mathrm{kg}=0.6 \mathrm{kg}$. Let $x$ kg of pure salt be added. Then, $\frac{0.6+x}{30+x}=\frac{10}{100} \Leftrightarrow 60+100 x=300+10 x \Leftrightarrow 90 x=240 \Leftrightarrow x=\frac{8}{3}=2 \frac{2}{3}$.