Chapter 5, Problem 55PS

Smartphone adoption among American teens has increased substantially. and mobile access to the Internet is pervasive. One in four teenagers are "cell mostly" Internet users-that is. they

mostly go online using their phone and not. using some other device such as a desktop or laptop computer.

If a sample of 10 American teens is selected, what is the probability that

a. 4 ate “cell mostly" Internet users?

b. at least 4 ate “cell mostly" Internet users?

c. at most 8 are "cell mostly� Internet users?

d. If you selected the sample in a particular geographical area and found that none of the 10 respondents ale “cell mostly� Internet users, what conclusions might you reach about whether the percentage of “cell mostly" Internet users in this area was $25\%?$