Question

The best fit line represents the relationship between the length of the first metacarpal bone and height for $9$ people. What would be the best interpretation of the slope of the line of best fit ?

• A. The predicted height increase in centimeters for one centimeter increase in the first metacarpal bone
• B. The predicted first metacarpal bone increase in centimeters for every centimeter increase in height
• C. The predicted height in centimeters of a person with a first metacarpal bone length of $0$ centimeters
• D. The predicted first metacarpal bone length in centimeters for a person with a height of $0$ centimeters

Answer 1

The correct option is A The predicted height increase in centimeters for one centimeter increase in the first metacarpal bone

The slope is the change in the vertical distance divided by the change in the horizontal distance between any two points on a line.

In this context, the change in the vertical distance is the change in the predicted height of a person, and the change in the horizontal distance is the change in the length of his or her first metacarpal bone.

The unit rate, or slope, is the increase in predicted height for each increase of $1$ centimeter of the first metacarpal bone.
Hence choice A is correct.