9. Heights of Tall Buildings A researcher estimates that the average height of the buildings of 30 or more stories in a large city is at least 700 feet. A random sample of 10 buildings is selected, and the heights in feet are shown. At a = 0.025, is there enough evidence to reject the claim? Undergraduate Enrollment It has been found that 485 511 841 725 615 85.6% of all enrolled college and university students in 520 535 635 616 582 the United States are undergraduates. A random sample Source: Pittsburgh Tribune-Review. of 500 enrolled college students in a particular state revealed that 420 of them were undergraduates. Is there sufficient evidence to conclude that the proportion 8. Commute Time to Work A survey of 15 large U.S. differs from the national percentage? Use a = 0.05. cities finds that the average commute time one way is Source: Time Almanac. 25.4 minutes. A chamber of commerce executive feels that the commute in his city is less and wants to publicize this. He randomly selects 25 commuters and finds the average is 22.1 minutes with a standard deviation of 5.3 minutes. At a = 0.10, is he correct? Source: New York Times Almanac. 13 /10