Chapter 10: 10.9 The normal range for a widely accepted measure of body size, the body mass index (BMI), ranges from 18.5 to 25. Using the mid-range BMI score of 21.75 as the null hypothesized value for the population mean, test this hypothesis at the .01 level of significance given a random sample of 30 weight-watcher participants who show a mean BMI=22.2 and a standard deviation of 3.1. Question: Calculations or Logic: Answer: Step 1 What is the research problem? Step 2 What is the null hypothesis? What is the alternative hypothesis? Step 3 What is the decision rule? Step 4 What is the value of the observed z? (you will need to calculate this) Step 5 What is the decision? (retain or reject the null hypothesis at the specified level of significance; note the relationship between the observed and critical z scores) Step 6 What is your interpretation of the decision in relation to the original research problem? 10.10 Let’s assume that over the years, a paper and pencil test of anxiety yields a mean score of 35 for all incoming college freshmen. We wish to determine whether the scores of a random sample of 20 new freshmen, with a mean of 30 and a standard deviation of 10, can be viewed as coming from this population. Test at the .05 level of significance. Question: Calculations or Logic: Answer: Step 1 What is the research problem? Step 2 What is the null hypothesis? What is the alternative hypothesis? Step 3 What is the decision rule? Step 4 What is the value of the observed z? (you will need to calculate this) Step 5 What is the decision? (retain or reject the null hypothesis at the specified level of significance; note the relationship between the observed and critical z scores) Step 6 What is your interpretation of the decision in relation to the original research problem? 10.11 According to the California Educational Code, students in grades 7–12 should receive 400 minutes of physical education every 10 school days. A random sample of 48 students has a mean of 385 minutes and a standard deviation of 53 minutes. Test the hypothesis.