Question

Many teens have posted profiles on a social-networking website. A sample survey in 2007 asked a random sample of teens with online profiles if they included false information in their profiles. Of 170 younger teens (aged 12 to 14), 113 said "yes." Of 317 older teens (aged 15 to 17), 150 said "yes."

(a) Do these samples satisfy the guidelines for the large-sample confidence interval?

A.) No, because the sample sizes differ too much.

B.) Yes, because the samples are larger than 40.

C.) Yes, because the sample size is more than 5 in each group.

D.) Yes, because the numbers of successes and failures are more than 10 in both samples.

(part b) Give a 95% large sample confidence interval for the difference between the proportions of younger and older teens who include false information in their online profiles. (Use P younger − P older. Round your answers to four decimal places.)

_____ to _____ FILL IN THE BLANKS

Answer 1

Solution:

a) answer is B. Yes, because the samples are larger than 40.

b) 95% CI for p1-p2 is: