Suppose that in the aerobic exercise group we also measured the number of hours of aerobic exercise per week and the mean is 5.2 hours with a standard deviation of 2.1 hours. The sample correlation is -0.42.

a)Is there evidence of a significant correlation between number of hours of exercise per week and HDL cholesterol level? Run the test at a 5% level of significance.
b) Estimate the equation of the regression line that best describes the relationship between number of hours of exercise per week and HDL cholesterol level (Assume that the dependent variable is HDL level).
c) Estimate the HDL level for a person who exercises 7 hours per week.
d) Estimate the HDL level for a person who does not exercise.