Total amount of the mixture = ounces
Proportion of formula =
Proportion of water =
Amount of water needed to make the mixture can be given as:
Total amount of mixture x Proportion of water
Using the values, we get:
Amount of water needed = = 7 ounces
Similarly the amount of formula needed will be:
Total amount of mixture x Proportion of formula
Using the values, we get:
Amount of formula needed = = 3.5 ounces
Therefore, the home health care assistant needs 3.5 ounces of formula and 7 ounces of water to prepare 10 and a half ounces of formula.