12.52 Predicting cell phone weight Refer to the cell phone data file on the book’s website. Regress y = weight on x = capacity of battery, excluding the outlier (phone no. 70).

a. Stating the necessary assumptions, find a 95% confidence interval for the mean weight of cell phones with a battery capacity of 1500mAh. Interpret the interval.

b. Find a 95% prediction interval for the weight of a cell phone with a battery capacity of 1500mAh. Interpret.

c. Explain the difference between the purposes of the intervals in part a and part b.