The total kilocalories and grams of fat for some typical meals at fast-food restaurants are listed here. Calculate the number of kilocalories and the percentage of total kilocalories from fat (1 gram of fat = 9 kcal). Round answers to the tens place.
a. a beef burrito, 470 kcal, 21 g of fat

Verified step by step guidance

1. Step 1: Understand the problem. You are tasked with calculating two things: (1) the number of kilocalories from fat in the beef burrito and (2) the percentage of total kilocalories that come from fat. You are given that 1 gram of fat provides 9 kcal, the total kilocalories of the burrito is 470 kcal, and the burrito contains 21 grams of fat.
2. Step 2: Calculate the kilocalories from fat. Use the formula: $\mathrm{kcal}=\mathrm{grams}\times 9$. Substitute the given value of 21 grams of fat: $21\times 9$.
3. Step 3: Calculate the percentage of total kilocalories from fat. Use the formula: $\mathrm{Percentage}=\frac{\mathrm{kcal}from\mathrm{fat}}{\mathrm{total}}\times 100$. Substitute the values: $\frac{21\times 9}{470}\times 100$.
4. Step 4: Perform the calculations. First, multiply 21 grams of fat by 9 kcal/gram to find the kilocalories from fat. Then, divide the kilocalories from fat by the total kilocalories (470 kcal) and multiply by 100 to find the percentage.
5. Step 5: Round the results to the tens place as instructed. Ensure both the kilocalories from fat and the percentage are rounded appropriately before reporting the final values.

Key Concepts

Caloric Calculation

Caloric calculation involves determining the total energy content of food, measured in kilocalories (kcal). To find the total kilocalories from fat, multiply the grams of fat by 9, since each gram of fat provides 9 kcal. This calculation is essential for understanding the energy contribution of macronutrients in a meal.

Percentage of Total Kilocalories

Calculating the percentage of total kilocalories from fat requires dividing the kilocalories derived from fat by the total kilocalories of the meal and then multiplying by 100. This percentage helps assess the proportion of energy coming from fat, which is important for nutritional analysis and dietary planning.

Nutritional Labeling

Nutritional labeling provides information about the macronutrient composition of food items, including total kilocalories and grams of fat. Understanding how to read and interpret these labels is crucial for making informed dietary choices, especially in fast-food contexts where meals can be high in calories and fat.