Because of a fortunate change in work schedules, we were able to reevaluate the subjects referred to in Exercise 10.1 for performance on the same tasks in the evening. The data are given below.

Peak time of day: 000000000 0 Performance rating: 40 60 40 50 30 40 50 50 20 30 Peak time of day: 000111111 1 Performance rating: 40 50 30 30 50 50 40 50 40 60

a. Plot these data and fit a regression line.

b. Calculate and test it for significance.

c. Interpret the results.