12.22 Battery capacity Refer to the cell phone data set from Exercise 12.9 about various specs of cell phones. Treat the weight of the phone as the response and the capacity of the battery as the explanatory variable. Remove the outlier (phone no. 70).

a. Is there evidence for an association between these two variables? Show all steps of a relevant significance test with significance level 0.05 and interpret.

b. Confirm, using the output of the software, that the 95% confidence interval for the population slope equals (0.028, 0.060). Interpret the interval and explain the correspondence with the result of the significance test in part a.