16a, b, c, 17, 18

16. Among 238 cell phone owners aged 18-24 surveyed by the Pew Research Center, 102 said their phone was an Android phone. a) Find a point estimate for the proportion of cell phone owners aged 18-24 who have an Android phone. b) Construct a 95% confidence interval for the proportion of cell phone owners aged 18-24 who have an Android phone. c) Assume that an advert claimed that 45% of cell phone owners aged 18-24 have an Android phone. Does the confidence interval contradict this claim? 17. In a preliminary study, a simple random sample of 100 computer chips was tested, and 17 of them were found to the defective. Now another sample will be drawn in order to construct a 95% confidence interval for the proportion of chips that are defective. Use the results of the preliminary study to estimate the sample size needed so that the confidence interval will have a margin of error of 0.06. 18. A pollster is going to sample a number of voters in a large city and construct a 98% confidence interval for the proportion who support the incumbent candidate for mayor. Find a sample size so that the margin of error will be no larger than 0.05