Nine adolescents are interviewed about the number of hours per week they work and the number of times they have smoked marijuana in the last year. The results are recorded as follows:

X: Number of hours worked per week 0 10 10 15 5 30 20 40 15

Y: Number of times smoked marijuana

in the last year 1 3 2 5 0 13 10 20 25

a. Calculate the regression coefficient b, and explain what it means in plain English.

b. Calculate the value of the Y-intercept, b₀.

c. Calculate a test of statistical significance for the regression coefficient b.