1. poll of 1044 U.S. adults split the sample into four age groups: ages 18-29, 30-49, 50-64, and 65+. In the youngest age group, 58% said that they thought the U.S. was ready for a woman president, as opposed to 39% who said "no, the country was not ready" (3% were undecided). The sample included 261 18- to 29-year olds. a) Do you expect the 90% confidence interval for the true proportion of all 18- to 29-year olds who think the U.S. is ready for a woman president to be wider or narrower than the 90% confidence interval for the true proportion of all U.S. adults? b) Construct a 90% confidence interval for the true proportion of all 18- to 29-year olds who believe the U.S. is ready for a woman president. a) The 90% confidence interval for the true proportion of 18- to 29-year olds who think the U.S. is ready for a woman president will be about the true proportion of all U.S. adults who think this. as wide as the 90% confidence interval for b) The 90% confidence interval is %. (Round to one decimal place as needed.)

2. A recent study found that 38% of college students engage in binge drinking (5 drinks at a sitting for men, 4 for women). After hearing of the result, a professor surveyed a random sample of 285 students at his college and found that 98 admitted to binge drinking in the last week. Should he be surprised at this result? Explain. Select the correct choice below and fill in the answer box to complete your choice. (Round to three decimal places as needed.) A. No, because the observed proportion of is less than 2 standard deviations below the survey result. O B. Yes, because the observed proportion of is greater than 2 standard deviations above the survey result. O C. Yes, because the observed proportion of is greater than 2 standard deviations below the survey result. O D. No, because the observed proportion of is less than 2 standard deviations above the survey result.

3. A developer wants to know if the houses in two different neighborhoods were built at roughly the same time. She hires an assistant to collect a random sample of houses from each neighborhood and finds that the summary statistics for the two neighborhoods are as shown. Complete parts a through c below. a) Find the estimated mean age difference, y, - Y, between the two neighborhoods. The estimated mean age difference between the two neighborhoods is years. (Type an integer or a decimal.) b) Find the standard error of the estimated mean difference SE (Y1 -Y2) = years (Round to two decimal places as needed.) c) Calculate the t-statistic for the observed difference in mean ages assuming that the true mean difference is 0. t= (Round to two decimal places as needed.)