3. Osteoporosis is a degenerative disease that primarily affects women over the age of 60. A research analyst wants to forecast sales of StrongBones, a prescription drug for treating this debilitating disease. She uses the model Sales = $\beta_0$ + $\beta_1$Population + $\beta_2$Income + $\epsilon$, where Sales is the sales of StrongBones (in $1,000,000s), Population is the number of women over the age of 60 (in millions), and Income is the average income of women over the age of 60 (in $1,000s). She collects data on 38 cities across the United States and obtains the following regression results:
Coefficients Standard error t stat p-value
Intercept 10.35 4.02 2.57 0.0199
Population 8.47 2.71 3.12 0.0062
Income 7.62 6.63 1.15 0.2661
a. Interpret the slope coefficients.
b. Predict sales if a city has 1.5 million women over the age of 60 and their average income is $44,000.
