Question

You have a 2 litre jug of 3.5% milk (milk that contains 3.5% fat). How much skim milk (0% fat) do you need to add to it to obtain milk which will have 2% fat?

Answer 1

3.5% of 2 litres is 0.07 litres. (0.035 * 2 = 0.07)

0.07 litres is 2% of 3.5 litres. (0.07 / 0.02 = 3.5)

This means you have to add 1.5 litres of skim milk to get a mixture with 2% fat.