The variable "2013 Cost" represents the four-year cost including tuition, supplies, room and board. The variable "Annual ROI" represents the return on investment for graduates of the school. It essentially represents how much you would earn on the investment of attending the school. The variable "Grad Rate" represents the graduation rate of the school.
Go to www.pearsonhighered.com/ sullivanstats to obtain the data file 4_2_28 using the file format of your choice for the version of the text you are using.
(a) In Problem 47 from Section 4.1, we saw that a scatter diagram between 2013 Cost and Grad Rate treating 2013 Cost as the explanatory variable suggested a positive association between the two variables. Find the least-squares regression line treating 2013 Cost as the explanatory variable. Round the slope to six decimal places.
(b) Interpret the slope.
(c) Washington University in St. Louis has a four-year cost of $234,600 and a graduation rate of 94%. Is Washington University's graduation rate above or below average among schools that cost $234,600?
(d) A scatter diagram between cost and return on investment (treating cost as the explanatory variable) suggested a negative association between the two variables. Find the least-squares regression line treating cost as the explanatory variable. Round the slope to seven decimal places.
(e) Interpret the slope.
(f) Washington University's return on investment is 6.1%. Is this above or below average among all schools that cost $234,600?