The coefficient of determination R2 of a set of data points

The coefficient of determination (R^2) of a set of data points is 0.81 (or 81%) and the slope of the regression line is -7. What is the correlation of the data? (show all the details,pls)

Solution

The correlation is the r value.

If r has the same sign as the slope.

As slope = -7, then our r is negative here.

As

r^2 = 0.81

Taking the NEGATIVE square root,

r = -sqrt(0.81)

r = -0.9 [ANSWER]