8.2.1 Salad Dressing Recipe

Activity symbolActivity: Salad Dressing Recipe

You have a recipe for salad dressing that serves 8  but want to know what proportion the oil and vinegar are in so that you can make it for any number of servings.

The recipe is:

  • 50 ml olive oil
  • 15 ml white wine vinegar

Work out the ratio of oil to vinegar.

Hint symbol


To find the ratio of two values, you should use division.

Solution symbol


For the oil to vinegar ratio, you should set up the calculation volume of oil divided by volume of vinegar.

Ratio of oil to vinegar equals times 50 ml divided by 15 ml times equals 3.3333 left parenthesis to four d full stop p full stop right parenthesis

So there is 3.333 times the volume of oil in the recipe compared to vinegar.

You will have noticed that this produces an answer where the 3 to the right of the decimal place is repeated.  In fact this continues to infinity and is known as a recurring number.  In this case 0.3 recurring is the same as 1 third.  Try dividing 1 by 3 on your calculator to check this out.

In this example, you calculated the ratio of one quantity to a second quantity by dividing the first number by the second. You can use this process to calculate other ratios, too.

8.2.2 To Buy or Not to Buy?