For Exercises 2 through 12, perform each of these steps. Assume that all variables are normally or approximately
a. State the hypotheses and identify the claim.
b. Find the critical value(s).
c. Compute the test value.
d. Make the decision.
e. Summarize the results.
Use the traditional method of hypothesis testing unless otherwise specified.
4. Obstacle Course Times An obstacle course was set up on a campus, and 8 randomly selected volunteers were given a chance to complete it while they were being timed. They then sampled a new energy drink and were given the opportunity to run the course again. The “before” and “after” times in seconds are shown. Is there sufficient evidence at α = 0.05 to conclude that the students did better the second time? Discuss possible reasons for your results.
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Chapter 9 Solutions
ELEMENTARY STATISTICS: STEP BY STEP- ALE
- Use the traditional method in testing the hypothesis in the problems below. In each problem, state the following:a. State the hypotheses and identify the claim.b. Find the critical value(s)c. Find the test value The manager of the cosmetics section of a large department store wants to determine whether newspaper advertising really does affect sales. For her experiment, she randomly selects 15 items currently in stock and proceeds to establish a baseline. The 15 items are priced at their usual competitive values, and the quantity of each item sold for a 1-week period is recorded. Then, without changing their price, she places a large ad in the newspaper, advertising the 15 items. Again, she records the quantity sold for a 1-week period. The results follow. Item 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15No. of Items Sold Before Ad 25 18 3 42 16 20 23 32 60 40 27 7 13 23 16No. of Items Sold After Ad 32 24 7 40 19 25 23 35 60 43 28 11 12 32 28arrow_forwardExpress the null hypothesis and the alternative hypothesis in symbolic form. Use the correct symbol (μ or p) for the indicated parameter.The mean college professors' salary is claimed to be over $80,300.arrow_forwarda. State the hypotheses and identify the claim. b. Find the critical value c. Compute the test value. d. Make the decision e. Summarize the results. Undergraduate Enrollment It has been found that 85.6% of all enrolled college and university students in the United States are undergraduates. A random sample 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 differs from the national percentage? Use a=0.05arrow_forward
- b and carrow_forwardneed b,c ,d not Aarrow_forwardDescribe type I and type II errors for a hypothesis test of the indicated claim. A furniture store claims that at least 40% of its new customers will return to buy their next piece of furniture. Describe the type I error. Choose the correct answer below. OA. A type I error will occur when the actual proportion of new customers who return to buy their next piece of furniture is at least 0.40, but you fail to reject Ho: p20.40. OB. A type I error will occur when the actual proportion of new customers who return to buy their next piece furniture is at least 0.40, but you reject Ho: p20.40. OC. A type I error will occur when the actual proportion of new customers who return to buy their next piece of furniture is no more than 0.40, but you reject Ho: p ≤ 0.40. OD. A type I error will occur when the actual proportion of new customers who return to buy their next piece f furniture is no more than 0.40, but you fail to reject Ho: p ≤0.40. Describe the type II error. Choose the correct answer…arrow_forward
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