8.2.4 Ratios in Food and Drink

Activity symbolActivity: Using Ratios in Food and Drink

(a) A fruit drink has to be diluted by mixing 1 ounce of the concentrate with 5 ounces of water. How much water should be added to 4 ounces of concentrate? How much drink will this make?

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Comment

Have you considered drawing a sketch of a glass with ounces marked along its side?

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Answer

(a) The ratio of concentrate to water is 1:5, so five times as much water as concentrate is required. If 4 ounces of concentrate is used, five multiplication four ounces equals 20 ounces of water is needed. If 4 ounces of concentrate and 20 ounces of water are used, the amount of drink will be four ounces prefix plus of 20 ounces equals 24 ounces.

(b) The ratio of white flour to wholemeal flour in a bread recipe is 3:7. If 6 ounces of white flour is used, how much wholemeal flour is needed? Can you explain why this is called a “70% wholemeal loaf”?

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Comment

Because the ratio is 3:7, this means 6 ounces of white flour is equivalent to 3 parts. How much is 1 part of white flour?

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Answer

[ Alternatively, you could use the corresponding fraction three divided by seven and find an equivalent fraction where the numerator is 6 (because there are 6 ounces of white flour). ]

(b) The resulting denominator would be your answer.

If 3 parts are equivalent to 6 ounces, one part is equivalent to six ounces prefix division of three equals two ounces. 7 parts are equivalent to seven multiplication two ounces equals 14 ounces. Thus, 14 ounces of wholemeal flour are needed.

There are 10 parts altogether, and 7 parts are wholemeal, so the fraction of the flour that is wholemeal is seven divided by 10 or 70%; hence the name.

Notice that there are different ways of tackling these problems and sketches might help you to understand the situation better.

8.2.3 Ratios in Recipes

8.3 Extensions and Further Exploration