CR13.9 Consider the following data on y 5 number of songs stored on an MP3 player and x 5 number of months the user has owned the MP3 player for a sample of 15 owners of MP3 players.

x y 23 486 35 747 2 81 28 581 5 117 32 728 23 445 10 128 4 61 26 476 1 35 8 121 13 266 9 126 5 141

a. Construct a scatterplot of the data. Does the relationship between x and y look approximately linear?

b. What is the equation of the estimated regression line?

c. Do you think that the assumptions of the simple linear regression model are reasonable? Justify your answer using appropriate graphs.

d. Is the simple linear regression model useful for describing the relationship between x and y? Test the relevant hypotheses using a significance level of .05.