Question

a pediatrician wants to determine the relation that may exist between a childs height and head circumference. she randomly selects 8 children from her practice, measures their height and head circumference, and obtains the data shown in the table. complete parts (a) through (e).

height (in.) head circumference (in.)
27.75 17.4
25.75 17.2
26.5 17.2
25.75 16.9
28 17.5
26.5 17.3
25.75 17.1
27 17.4

click here to see the table of critical values for correlation coefficient.

(a) if the pediatrician wants to use height to predict head circumference, determine which variable is the explanatory variable and which is the response variable.

the explanatory variable is height and the response variable is head circumference.

the explanatory variable is head circumference and the response variable is height.

(b) draw a scatter diagram. which of the following represents the data?

Explanation:

In a scatter - diagram, the explanatory variable is plotted on the x - axis and the response variable on the y - axis. Since height is the explanatory variable and head circumference is the response variable, height (in inches) should be on the x - axis and head circumference (in inches) on the y - axis.

• Option A has height on the x - axis and head circumference on the y - axis.
• Option B has height on the y - axis and head circumference on the x - axis.
• Option C has height on the x - axis and head circumference on the y - axis, but let's check the range of values. The height values range from 25.75 to 28 and head circumference from 16.9 to 17.6. Option C has the correct axes labels (height on x, head circumference on y) and the range of values for both variables.
• Option D has head circumference on the x - axis and height on the y - axis.

Answer:

C.