A researcher is interested in examining whether self-affirming oneself leads to decreased anxiety in response to threatening information. The researcher conducts a research study in which an individual is self-affirmed prior to receiving threatening information. Researchers know that, on average, individuals tend to have anxiety levels of µ = 10 with a standard deviation of σ = 2 when presented with this threatening information. If a self-affirmed individual has an anxiety level of X = 5 following the threatening message, it is reasonable to conclude that self-affirmation ______. a. increases anxiety levels following threatening information. b. does not have an influence on anxiety levels following threatening information. c. does have an influence on anxiety levels following threatening information. d. This is impossible to determine based on the information provided.

Citrus Rental is a popular car rental agency that has a history of having too few cars available, so that its available cars are overdriven. The mean monthly mileage over the years for Citrus cars has been about 1500 miles per month. Recently, though, Citrus purchased thousands of new cars, and the company claims that the average mileage of its cars is now less than in the past. To test this, a random sample of 11 recent mileages of Citrus cars was taken. The mean of these 11 mileages was 1332 miles per month, and the standard deviation was 232 miles per month. Assume that the population of recent monthly mileages of Citrus cars is normally distributed. At the 0.05 level of significance, can it be concluded that the mean recent monthly mileage, u, of Citrus cars is less than 1500 miles per month? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified in the table. (If necessary,…

A recent survey of 1030 U.S. adults selected at random showed that 627 consider the occupation of firefighter to have very great prestige. Estimate the probability (to the nearest hundredth) that a U.S. adult selected at random thinks the occupation of firefighter has very great prestige.

An English teacher has been teaching a sixth grade composition class for many years.  He has the feeling that over the past several years, the writing ability of students has changed.  A national test of proficiency in composition was administered 5 years ago.  The resulting distribution of scores was normally shaped, had a mean of 85 and a standard deviation of 10.9.  In order to test his feeling, he gives his present class of 43 students the same proficiency test.  The resulting mean is 80 and the standard deviation is 8.7.     a. What is the alternative hypothesis?   b. What is the null hypothesis?   c. What is your conclusion, using á = 0.052 tail?   d. What type error may you be making because of your conclusion in part c?

Dr. Jill Biden has been teaching a seventh grade English composition class for many years.  She has the feeling that over the past several years, the writing ability of students has changed.  A national test of proficiency in composition was administered 5 years ago.  The resulting distribution of scores was normally shaped, had a mean of 85 and a standard deviation of 10.9.  In order to test his feeling, she gives her present class of 43 students the same proficiency test.  The resulting mean is 80 and the standard deviation is 8.7.          a.   What is the alternative hypothesis?         b.   What is the null hypothesis?         c.   What is your conclusion, using an alpha of 0.05 (2 tailed).         d.   What type of error might you be making because of your conclusion in part c?

A psychologist is studying the self image of smokers, as measured by the self-image (SI) score from a personality inventory. She would like to examine the mean SI score, µ, for the population of all smokers. Previously published studies have indicated that the mean SI score for the population of all smokers is 80 and that the standard deviation is 15, but the psychologist has good reason to believe that the value for the mean has changed. She plans to perform a statistical test. She takes a random sample of SI scores for smokers and computes the sample mean to be 88. Based on this information, complete the parts below. (a) What are the null hypothesis H. and the alternative hypothesis H₁ that should be used for the test? Ho : H₁ :0 (b) Suppose that the psychologist decides not to reject the null hypothesis. What sort of error might she be making? Type I Suppose the true mean SI score for all smokers is 80. Fill in the blanks to describe a Type I error. the hypothesis that u is (Choose…

Risk taking is an important part of investing. In order to make suitable investment decisions on behalf of their customers, portfolio managers give a questionnaire to new customers to measure their desire to take financial risks. The scores on the questionnaire are approximately normally distributed with a mean of  49  and a standard deviation of  16 . The customers with scores in the bottom  15%  are described as "risk averse." What is the questionnaire score that separates customers who are considered risk averse from those who are not? Carry your intermediate computations to at least four decimal places. Round your answer to one decimal place.

Many psychologists are concerned that the average level of anxiety in children has increased over the past 40 years. In the 1980s, the population average score on the Child Manifest Anxiety Scale (CMAS) was 15.1. In 2021, a random sample of 101 children was tested with CMAS. The mean for the sample was 16.1 with the standard deviation of 4. Is there enough evidence to claim that there has been a significant change in the average level of anxiety since the 1980s? Conduct the appropriate statistical test (two- tailed) with a = .05. Based on the estimated Cohen's d, the magnitude of change in the average level of anxiety since the 1980s could best be qualified as: O Very large O Large O No change OSmall