Final answer:
The unit rate for the situation with 720 calories in 9 servings is 80 calories per serving, which can also be expressed as 334,720 joules of energy per serving.
Step-by-step explanation:
To determine the unit rate of calories per serving, we divide the total number of calories by the number of servings. The question states that there are 720 calories in 9 servings. So, we calculate the unit rate by dividing 720 by 9.
720 calories ÷ 9 servings = 80 calories per serving
This unit rate tells us the number of calories in one serving of food. Since the question is about energy content, we can also convert this into joules. One kilocalorie (Calorie with a capital C) equals 4184 joules. Therefore, to convert 80 Calories to joules:
80 kilocalories x 4184 joules/kilocalorie = 334,720 joules per serving
The student can now understand that each serving of the breakfast cereal contains 80 Calories or 334,720 joules of energy, which is the unit rate for this situation.