Exam 9: Hypothesis Tests

Exhibit 9-6 A random sample of 16 students selected from the student body of a large university had an average age of 25 years and a standard deviation of 2 years. We want to determine if the average age of all the students at the university is significantly more than 24. Assume the distribution of the population of ages is normal. -Refer to Exhibit 9-6. At 95% confidence, it can be concluded that the mean age is

A weatherman stated that the average temperature during July in Chattanooga is 80 degrees or less. A sample of 32 Julys is taken. The correct set of hypotheses is

The average life expectancy of tires produced by the Whitney Tire Company has been 40,000 miles. Management believes that due to a new production process, the life expectancy of their tires has increased. In order to test the validity of their belief, the correct set of hypotheses is

Exhibit 9-2 n = 64 = 50 s = 16 H₀: $\mu$ 54 H_a: $\mu$ < 54 -Refer to Exhibit 9-2. The p-value is between

A sample of 30 cookies is taken to test the claim that each cookie contains at least 9 chocolate chips. The average number of chocolate chips per cookie in the sample was 7.8 with a standard deviation of 3. a.State the null and alternative hypotheses. b.Using the critical value approach, test the hypotheses at the 5% level of significance. c.Using the p-value approach, test the hypothesis at the 5% level of significance. d.Compute the probability of a Type II error if the true number of chocolate chips per cookie is 8.

For a one-tailed hypothesis test (upper tail) the p-value is computed to be 0.034. If the test is being conducted at 95% confidence, the null hypothesis

The p-value ranges between

Exhibit 9-9 The sales of a grocery store had an average of $8,000 per day. The store introduced several advertising campaigns in order to increase sales. To determine whether or not the advertising campaigns have been effective in increasing sales, a sample of 64 days of sales was selected. It was found that the average was $8,300 per day. From past information, it is known that the standard deviation of the population is $1,200. -Refer to Exhibit 9-9. The p-value is