According to a Nationwide Mutual Insurance Company Driving While Distracted Survey conducted in 2008, 80% of the drivers interviewed said that they have talked on their cell phones while driving (The...

Bus-173 (Applied Statistics)

Extracted text: According to a Nationwide Mutual Insurance Company Driving While Distracted Survey conducted in 2008, 80% of the drivers interviewed said that they have talked on their cell phones while driving (The New York Times, July 19, 2009). The survey included drivers aged 16 to 61 years selected from 48 states. Assume that this result holds true for the 2008 population of all such drivers in the United States. In a recent random sample of 800 drivers aged 16 to 61 years selected from the United States, 85% said that they have talked on their cell phones while driving. (a) What is the point estimate of proportion of drivers who did not talk on their cell phones while driving? (b) Mention required conditions of the large sample for testing proportion and check these for the above problem. (c) Test at 5% level of significance the hypothesis that the current percentage of such drivers who have not talked on their cell phones while driving is less than 20%.