8. In a survey of 3611 adult Americans 18 years and older conducted in July 2010 by Smart Revenue, it was found that 1542 have used their smartphone to make a purchase. 3. Calculate the point estimate for the population proportion of adult Americans 18 years and older who have used their smartphone to make a purchase. b. Construct a 90% confidence interval for the population proportion of adult Americans who have used their smartphone to make a purchase. c. Interpret the interval. HINT: Consider #7. 9. Wendy, a candidate in a two-person election commissions a poll to determine who is ahead. The pollster randomly chooses 500 registered voters and determines that 260 out of the 500 favor Wendy. 3. Obtain a point estimate for the population proportion of registered voters who prefer Wendy. b. Construct a 95% confidence interval for the population proportion of registered voters who prefer Wendy. c. Based on the Cl above, is there evidence that a majority of voters favor Wendy? 10. How do you know when to use ofthe t-table? When do we use of the Standard Normal z-table