• # question_answer Sea water contains 5% salts by weight. How many kilogram of fresh water must be added to 60 kg of sea water for the content of salt in solution to be made 3%? A)  10 kg   B)  20 kg C)  30 kg    D)  40 kg

Let x kg of fresh water is added to sea water. $\frac{{{q}_{salt}}}{({{q}_{salt}}+{{q}_{water}})}=\frac{5%\,\,\text{of}\,60}{60+x}=\frac{3}{100}$ (given, 3% salt in solution) $\Rightarrow$ $\frac{3}{60+x}=\frac{3}{100}$ $\therefore$ $x=40\,\,kg$ So, 40 kg of fresh water must be added to sea water.