Beer and BAC, I How much does drinking beer increase the alcohol content of your blood? Th is question was addressed in an experiment at Ohio State University. Sixteen students volunteered to participate. Before the experiment, each student blew into a Breathalyzer machine to show that their blood alcohol content (BAC) was at the zero mark. Th e student volunteers then drank a varying number (between 1 and 9) of 12-ounce beers. How much each student drank was assigned by drawing tickets from a bowl. About 30 minutes later, an offi cer from the OSU Police Department measured their BAC using the Breathalyzer. Here are the data:

(a) Suppose you want to estimate how a person’s BAC is aff ected by the number of beers he or she drinks. Make a scatterplot of BAC versus beers using the data in the table above. Which variable did you choose to be the y variable and which did you choose to be the x variable? Explain.

(b) Use your calculator to fi nd the correlation between BAC and beers. Is the correlation an appropriate measure of the strength of the association between BAC and beers? Explain briefl y.

(c) Use your calculator to fi nd the least-squares regression line for BAC on beers.
Interpret the slope and y intercept of the regression line.

Student: Beers: 1 5 22 2 3 2 9 48 4 5 3 67 6 73 7 3 85 BAC: 0.10 0.03 0.19 0.12 0.04 0.095 0.07 0.06 Student: 9 10 11 12 13 14 15 16 Beers: 3 5 4 6 5 7 1 4 BAC: 0.02 0.05 0.07 0.10 0.085 0.09 0.01 0.05