How much water must he add to get 5% salt solution?
Solution: Let us tabulate the information. It is given that the original solution has 4 ounces of salt and so the rest of it is water which is 12 – 4 = 8 ounces of water. The new solution has 4 ounces of salt and we must add some more water say x ounces to get 5% salt water solution. So the new solution has 4 ounces of salt and 8+x ounces of water. Now we have to set up equations 5% of (12+x) ounces of solution is salt which is 4 ounces, i.e. 0.05(12+x) = 4 x = 68 ounces Hence, the chemist must add 68 ounces of water to get a mixture of 5% salt water solution. It is very helpful to organize the data given in problems invoving mixtures in the form of a table. It is also useful to practice many types of problems involving mixtures so that we can recognize pattern.
