In a study on caffeine and stress, college students indicated how many cups of coffee they drink per day and their stress level on a scale of 1 to 10. The data are provided in the following table.
Number of Cups of Coffee Stress Level
3 5
2 3
4 3
6 9
5 4
1 2
7 10
3 5
2 3
4 8
Calculate a Pearson's r to determine the type and strength of the relationship between caffeine and stress level. How much of the variability in stress scores is accounted for by the number of cups of coffee consumed per day?