In a study nine tires of a particular brand were driven on a

In a study, nine tires of a particular brand were driven on a track under identical conditions. Each tire was driven a particular controlled distance (measured in thousands of miles) and the tread depth was measured after the drive. Tread depth is measured in “mils.” Here, 1 mil is 0.001 inch. The least-squares regression line was computed, and added to a scatterplot of these data.

The equation of the least-squares regression line is:

Tread depth = 360.64 ? 11.39x (thousands of miles)

Also, r² = 0.953. What is the correlation between tread depth and miles?

Select one:

a. -.953

b. -.976

c. .953

d. .976

Solution

correlation = sqrt(r2) = (sign of slope )* 0.97621718894926245813

b. -.976