Chapter 11.2, Problem 21E

Smartphone Battery Life. Battery life is an important issue for many smartphone owners. Public health studies have examined “low-battery anxiety” and acute anxiety called nomophobia that results when a smartphone user’s phone battery charge runs low and then dies (Wall Street Journal, https://www.wsj.com/articles/your-phone-is-almost-out-of-battery-remain-calm-call-a-doctor-1525449283). Battery life between charges for the Samsung Galaxy S9 averages 31 hours when the primary use is talk time and 10 hours when the primary use is Internet applications. Because the mean hours for talk time usage is greater than the mean hours for Internet usage, the question was raised as to whether the variance in hours of usage is also greater when the primary use is talk time. Sample data showing battery life between charges for the two applications follows.

1. a. Formulate hypotheses about the two population variances that can be used to determine if the population variance in battery life is greater for the talk time application.
2. b. What are the standard deviations of battery life for the two samples?
3. c. Conduct the hypothesis test and compute the p-value. Using a .05 level of significance, what is your conclusion?