A line of best fit shows the overall pattern, so it need not pass through every dot. Read two points on the drawn line, preferably where it crosses the vertical axis and another point far away. Use them to find the intercept and slope. A line that falls in the right direction can still have the wrong starting value or rate.
Hints
- Hint 1
The intercept is the line's heart-rate value at zero workouts. Read it from the drawn line, not from the nearest dot. What value does the line approach where it crosses the vertical axis?
- Hint 2
A slope measures heart-rate change per additional workout. Choose two points far apart on the drawn line, then divide the change in heart rate by the change in workouts. What sign should that rate have?
Step-by-step
Read the fitted line's intercept and slope
Step 1Read two points on the fitted line
The line is near and . Use points on the drawn line, not individual data dots, because the question asks for the fitted line's equation. Its intercept, the heart rate at zero workouts, is about beats per minute.
- Step 2
Find the heart-rate change per workout
The slope is heart-rate change divided by workout change. From the first point to the second, type in Desmos. It shows , so the line predicts about fewer beats per minute for each additional workout.
- Step 3
Match both parts of the equation
In slope-intercept form, , is the heart rate at and is its change per workout. Use both values from the line:
This models resting heart rate in beats per minute from workouts per week. Choice A.