Question

1. A Pew Research study regarding cell phones asked questions about cell phone experience. One growing concern is unsolicited advertising in the form of text messages. Pew asked 1150 cell phone owners, “Have you ever received unsolicited text messages on your cell pone from advertisers?” and 17% reported that they had.

a) State the parameter you want to estimate.

b) Check conditions and identify the appropriate inference method.

c) If the conditions have been met, perform the calculations for a 95% confidence interval. If conditions have not been met, state the condition that has been violated.

d) If you were able to complete c) interpret your interval in the context of the problem.

2. The 2013 International Bedroom Poll surveyed about 250 randomly sampled adult residents in each of six countries asking about their sleep habits. Sleep researchers generally report that People who regularly use their computers or laptops in the hour before trying to go to sleep are less likely to report getting a good night’s sleep..., more likely to be categorized as “sleepy”..., and more likely to drive drowsy... than their counterparts. The poll found that 128, or 51%, of 251 U.S. respondents reported using a computer, laptop, or electronic tablet in the hour before trying to go to sleep almost every night. By contrast, 162, or 65%, of 250 Japanese respondents made the same admission. What does a confidence interval say about \ the difference in sleep habits?

a) State the parameter you want to estimate.

b) Check conditions and identify the appropriate inference method.

c) If the conditions have been met, perform the calculations for a 95% confidence interval for the difference in proportions. If conditions have not been met, state the condition that has been violated.

d) If you were able to complete c) interpret your interval in the context of the problem.

3. In a March 2016 survey by Gallup of 1019 U.S. adults, 65% believe that global warming is due more to human activity than natural changes in the environment. The poll reports a margin of error of 4%. Suppose an environmental group planning a follow-up survey of voters’ opinions on global warming wants to determine a 95% confidence interval with a margin of error of no more than + 2%. How large a sample does the group need?

Answer 1

a)

p: Proportion of people received unsolicited text messages on cell pone from advertisers

b)

c)

d)

We are 95% confident that true proportion of people received unsolicited text messages on cell pone from advertisers lis in the interval (0.1482, 0.1918) or (14.82%, 19.18%).