49. PC World provided ratings for 15 notebook PCs (PC World, February 2000). The performance score is a measure of how fast a PC can run a mix of common business applications as compared to a baseline machine. For example, a PC with a performance score of 200 is twice as fast as the baseline machine. A 100-point scale was used to provide an overall rating for each notebook tested in the study. A score in the 90s is exceptional, while one in the 70s is good. Table 3.9 shows the performance scores and the overall ratings for the 15 notebooks.

a. Compute the sample correlation coefficient.

b. What does the sample correlation coefficient tell about the relationship between the performance score and the overall rating?