7.12 Auto exhaust and lead exposure. Researchers interested in lead exposure due to car exhaust sampled the blood of 52 police officers subjected to constant inhalation of automobile exhaust fumes while working traffic enforcement in a primarily urban environment. The blood samples of these officers had an average lead concentration of 124.32 µg/l and a SD of 37.74 µg/l; a previous study of individuals from a nearby suburb, with no history of exposure, found an average blood level concentration of 35 µg/l.º 9. (a) Write down the hypotheses that would be appropriate for testing if the police officers appear to have been exposed to a different concentration of lead. (b) Explicitly state and check all conditions necessary for inference on these data. (c) Regardless of your answers in part (b), test the hypothesis that the downtown police officers have a higher lead exposure than the group in the previous study. Interpret your results in context.

18-34 35-49 50-64 65+ Burger King 127 119 63 163 McDonald's 75 142 82 129 Wendy's 124 156 75 132

Hypothesis Test - Population ProportionThe percentage of Texans not covered by health care insurance in 2019 was 15%. Let p denote the proportion of those not covered by health care insurance in Texas. We would like to test the hypotheses H₀ : p ≤ 0.15 vs. Ha : p > 0.15 using a random sample of 100 Texans. The percentage of those who do not have health care insurance in the sample is 20%. What is the value of the test statistic?     0.95     1.4     1.25     2.25

True or false?

Making a Decision If your claim is in the null hypothesis and you fail to reject the null hypothesis, then your conclusion would be: There is sufficient evidence to warrant rejection of the original claim There is not sufficient sample evidence to support the original claim There is not sufficient evidence to warrant rejection of the original claim The sample data support the original claim

Subject Location Reading Math Science Is achieving a basic skill level related to the location of the school? The results of a random sample of students by the location of school and the number of students achieving basic skill levels in three subjects is shown in the contingency table. At a = 0.01, test the hypothesis that the variables are independent. Complete parts (a) through (d). Urban 48 41 39 Suburban 70 63 64 (a) Identify the claim and state the null and alternative hypotheses. Ho: Skill level in a subject is location. Ha: Skill level in a subject is location. The is the claim. (b) Calculate the test statistic. If convenient, use technology. %3D (Round to three decimal places as needed.) (c) Decide to reject or fail to reject the null hypothesis. Then interpret the decision in the context of the original claim. Choose the correct conclusion below. O A. Reject the null hypothesis. There is not enough evidence to reject the claim that skill level in a subject is independent of…

Part A

Computing the Z-test Statistic The State College is evaluating a new English composition course for freshmen. A random sample of n = 25 freshmen is selected from the State College. All 25 students are placed in the new English composition course during their first semester. One year later, a writing sample is obtained for each student and their writing samples are graded using a standardized evaluation technique. The average score for the sample is M= 76. For the general population of the State College, writing scores form a normal distribution with a mean = 70 and a standard deviation = 20.  Please calculate the appropriate hypothesis test using all four steps?

When performing a hypothesis test to decide whether a predictor variable is useful to make predictions, you observe that p>a. What does this mean? Reject HO: The predictor is useful to make predictions Reject HO: The predictor is not useful to make predictions O Do not reject HO: The predictor is useful to make prediction O Do not reject HO: The predictor is not useful to make predictions