Data on tuition and mid-career salary are collected from a number of universities and colleges. The result of the data collection is the linear regression model :
ˆy= −0.91x+161y^= -0.91x+161
where x = annual tuition and y = average mid-career salary of graduates, both in thousands of dollars.
1. Which quantity is the independent variable?
O annual tuition
O average mid-career salary of graduates
2. According to this model, what is the average salary for a graduate of a college or university where the annual tuition is $30,000? $ _______
3. What is the slope of this regression model?

1. An independent variable is the factor that is not determined by the model in this case the annual tuition variable (the linear regression model factor)

2. substitute $30,000 into the linear regressions equation gives:

y = -0.91(30000) + 161 = -27139

This value tells us that when the annual tuition is $30,000 the average mid-career salary of graduates is predicted to be -$27,139

3. the slope if the regression is represented by the coefficient of the factor in the linear regression model. In this case, as the factor is x or the annual tuition, and the coefficient of this variable in the given example is -0.91 which in turn is the slope of the model.