Question: The actual level of potassium in a person’s blood varies slightly from day to day. Suppose that in the long run, repeated measurements for the same person on different days vary normally with standard deviation 0.2. Use MINITAB to answer part (a).

(a) Suppose Julie’s potassium level was taken on 3 different days and the mean result is 3.2. Estimate, with 95% confidence, Julie’s mean day to day potassium level. (4 marks)

(b) It is believed that the mean day to day potassium level in a healthy person’s blood is 2.8. Based on the interval obtained in part (a), is there clear statistical evidence of a potassium imbalance in Julie’s blood stream? Explain. (4 marks)