8.81 A significance test for the Fox News app
Refer to the previous exercise.
8.81
(a) . (b) . The proportion of smartphone users who visit the Fox News website before the Fox News app was introduced is less than the proportion of smartphone users who visit the Fox News website after the Fox News app was introduced. It is likely that the app helps bring traffic to the Fox News website, hence the one-sided alternative. (Note: is also acceptable with a suitable argument.) (c) Assuming the samples were random and the samples were independent (that is, not the same group), then the conditions for the Normal distribution are met because we have at least 10 successes and failures in each sample.