To determine how many minutes a person needs to run to burn 100 calories based on the given table, we can follow these steps:
1. Understand the Ratio:
- The table indicates that 4 minutes of running burns 20 calories.
- The table also indicates that 8 minutes of running burns 40 calories.
2. Calculate Calories Burned Per Minute:
- First, find the number of calories burned per minute.
- Using the first row of the table: We know 4 minutes burns 20 calories, so the rate is [tex]\( \frac{20 \text{ calories}}{4 \text{ minutes}} \)[/tex].
[tex]\[
\text{Calories per minute} = \frac{20 \text{ calories}}{4 \text{ minutes}} = 5 \text{ calories per minute}
\][/tex]
3. Use the Calculated Rate:
- We need to find the number of minutes required to burn 100 calories.
- Knowing the rate is 5 calories per minute, we can set up the equation to solve for the required minutes.
[tex]\[
\text{Required minutes} = \frac{\text{Target Calories}}{\text{Calories per minute}}
\][/tex]
4. Plug in the Numbers:
[tex]\[
\text{Required minutes} = \frac{100 \text{ calories}}{5 \text{ calories per minute}} = 20 \text{ minutes}
\][/tex]
Therefore, to burn 100 calories, a person needs to run for 20 minutes. The correct answer is 20.
