Homework 14 #2

A sample of four 35-year-old males is asked about the average number of hours per week that he exercises, and is also given a blood cholesterol test. The data is recorded in the order pairs given below, in the form (Hours Exercising, Cholesterol Level):

Having a bit of trouble finding coefficient of correlation.

the covariance is -21.55 so I figure the coefficient of correlation would be the covariance/(Std deviation X)(Std deviation Y) which is -21.55/ (1.415)(15.329) which is -233.455, but this is incorrect.

What am I doing wrong?


  • This looks like a parentheses mistake. You've computed
    $$\frac{-21.55}{1.415} \times 15.329$$
    but I think you mean to compute
    $$\frac{-21.55}{1.415\times 15.329}.$$
    When you look at the thing that you're trying to compute, I think it's pretty clear that the absolute value should be less than 2 so that $-233.455$ is probably not reasonable.

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