Besides their known long-term effects, do cigarettes also cause short-term illnesses such as colds? To help answer this question, a sample of smokers was drawn. Each person was asked to report the average number of cigarettes smoked per day and the number of days absent from work due to colds last year. The following output was obtained as a result of conducting regression analysis using Excel. (Some values are hidden, and referred to as x1, x2 and x3 for the purpose of this question.)

a) What is the estimated regression equation?

b) What do the coefficients tell you about the relationship between smoking cigarettes and sick days because of cold days?

c) Find a point estimate for the number of days absent from work due to cold if a person smokes 10 cigarettes per day on the average.

d) What is the value of coefficient of determination? Comment on its value. (What does that imply in terms of this problem?)

e) To determine whether there is sufficient evidence to infer that a linear relationship exist, the following test is to be conducted:

H0: ?1 = 0, Ha: ?1 ? 0

How do you assess the linear model based on the above test? (Use ?=0.05).