In a psychology experiment, people improved their ability to recognize common verbal and semantic information with practice. Their judgment time after t days of practice was f (t) = .36 + .77(t - .5)^-0.36 seconds.

(a) Display the graphs of f (t) and f′(t) in the window [.5, 6] by [-3, 3]. Use these graphs to answer the following questions.

(b) What was the judgment time after 4 days of practice?

(c) After how many days of practice was the judgment time about .8 second?

(d) After 4 days of practice, at what rate was judgment time changing with respect to days of practice?

(e) After how many days was judgment time changing at the rate of -.08 second per day of practice?