1: What would be a natural null hypothesis for the research question of whether or not the average US passenger car gets more than 30 miles per gallon? What alternative hypothesis would you use?
2: Researchers used a random sample to test the null hypothesis that the average age of people visiting an Internet site is 25. Which of the following results has the higher t value for a test of this null hypothesis? Do not do any calculations; just explain your reasoning.
a. x ¼ 26:43; s ¼ 7:17; n ¼ 50
b. x ¼ 32:14; s ¼ 7:17; n ¼ 50
3: Which of the following results has the higher t value for a test of the null hypothesis that the average speed on a 40 miles-per-hour street is 40 miles per hour? Do not do any calculations; just explain your reasoning.
a. x ¼ 43:71; s ¼ 14:88; n ¼ 60
b. x ¼ 43:71; s ¼ 8:06; n ¼ 60
4: Which of the following assumptions were used in calculating the P value in the preceding exercise?
a. Temperatures for healthy adults are normally distributed.
b. These 50 observations are a random sample.
c. The mean temperature for unhealthy adults is higher than the mean temperature for healthy adults.
d. On average, healthy adults have a temperature of 98.6 Fahrenheit.