9.3.1 Math in Cooking

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The time to cook a fresh chicken depends on its mass, commonly called weight in everyday language, as given by the following formula:

cooking time in minutes equation left hand side equals right hand side 15 plus mass in grams divided by 500 multiplication 25

Roughly how long will a chicken with a mass of 2.2 kg take to cook?

To use the formula, you need to substitute the mass of the chicken into the right side of the equation and then work out the resulting calculation. However, the formula asks for the mass in grams, so the first step is to convert 2.2 kilograms (kg) into grams (g).

Since there are 1000 g in 1 kg, 2.2 kg equation left hand side equals right hand side 2.2 multiplication 1000 g equals 2200 g.

Substituting 2200 for the mass in grams gives: cooking time in minutes equation left hand side equals right hand side 15 plus 2200 divided by 500 multiplication 25.

Carrying out the multiplication and division first gives (remember PEMDAS!): cooking time in minutes equation sequence equals 15 plus 110 equals 125.

So, the cooking time would be about 125 minutes, or 2 hours and 5 minutes. If you prefer, you can use a calculator, but remember to make an estimate first so that you may check that your answer is reasonable.

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How long would it take to cook a chicken with a mass of 1.6 kg?

Answer Symbol

Answer

First, we must convert 1.6 kg into grams: 1.6 kg prefix multiplication of 1000 equals 1600 g.

The cooking time can then be calculated in minutes: 15 plus 1600 divided by 500 multiplication 25 equals 95 minutes.

The chicken would take about 95 minutes, or 1 hour and 35 minutes.

9.3.2 Math in Health Care