Childhood participation in sports, cultural groups and youth groups appears to be related to improved self-esteem for adolescents (McGee et al., 2006). A sample of n =100 adolescents with a history of group participation is given a standardized self-esteem questionnaire. For the general population of adolescents, scores on this questionnaire form a normal distribution with a mean of μ = 40 and a standard deviation of σ = 12. The sample of group participation adolescents had an average of M = 44. Is there enough evidence to conclude that self-esteem scores for these adolescents are significantly different from those of the general population? Use a two-tailed test with α=.05. Report the results in APA.

In a study investigating the effect of car speed on accident severity, 5,000 reports of fatal automobile accidents were examined, and the vehicle speed at impact was recorded for each one. For these 5,000 accidents, the average speed was 42 mph and the standard deviation was 12 mph. A histogram revealed that the vehicle speed at impact distribution was approximately normal. (Use the Empirical Rule.) (a) Approximately what percentage of vehicle speeds were between 30 and 54 mph? approximately  % (b) Approximately what percentage of vehicle speeds exceeded 54 mph? (Round your answer to the nearest whole number.) approximately  %

Consider the time it takes, in minutes, for police officers to respond to a 911 call, where a life-threatening crime (an armed robbery, an assault, a shooting) is in progress. For a particular police jurisdiction, the average response time is 20 minutes with a standard deviation of 3 minutes. Assuming the data is symmetric and using the Empirical rule, what %% of the response times fall between 17 to 23 minutes.

The National Assessment of Educational Progress (NAEP) is a nationwide assessment of students' proficiency in nine subjects: mathematics, reading, writing, science, the arts, civics, economics, geography, and U.S. history. The main NAEP assessments are conducted annually on samples of students from grades 4, 8, and 12. Suppose in 2000, the science scores for female students had a mean of 146 with a standard deviation of 35. Assume that these scores are normally distributed with the given mean and standard deviation. The normal curve representing this distribution of the scores is symmetrical about a vertical line through             .   The value 41 is        below the mean, and the value 251 is         above the mean. The area under the curve between 41 and 251 is approximately            .   Similarly, 95.44% of the female students scored between          and         .

Two brands of batteries are tested, and their voltages are compared. The summary statistics follow.  For sample 1, the sample size is 27; the population standard deviation is 0.3 volts and the mean is 9.2 volts. For sample 2, the sample size is 30; the population standard deviation is 0.1 volts and the mean is 8.8 volts. Is the mean of sample 1 smaller than the mean of sample 2? Using a significance level of 0.05.   a) Identify the claim and state the hypotheses.    b) What is the test statistics? Find the critical values (s). c) Make the decision to reject or not reject the null hypothesis and explain why. d) Graph your decision and include all the values. That is, the mean, the standard deviation, the critical value(s), the rejection region. e)    Set up the formula with the correct numbers for the 95% confidence interval of the mean number of jobs.

A report states that the mean yearly salary offer for students graduating with a degree in accounting is $48,722. Suppose that a random sample of 50 accounting graduates at a large university who received job offers resulted in a mean offer of $49,870 and a standard deviation of $3900. Do the sample data provide strong support for the claim that the mean salary offer for accounting graduates of this university is higher than the national average of $48,722? Ho: μ = Ha: (Put in the correct symbol and value) ✓ Select an answer a not = P-value: = ↑ Based on the above we choose to Select an answer Question Help: Post to forum Submit Question

Dr. Graham is interested in determining if middle-aged adults use text messaging more or less frequently than the general population. Dr. Graham collects information on text messaging from a random sample of 50 adults ages 25 to 44. Dr. Graham finds that these individuals send or receive an average of 68 text messages per day. Using the population mean (and standard deviation) of 41.5 texts per day (34 texts per day), determine whether adults in this age group use text messaging more than the general public.

Because schools in areas affected by these natural disasters were disproportionately low performing schools, many students affected were not only forced to switch schools, but also ended up switching to a higher quality school. Sacerdote finds initial declines in test scores (likely due to the shock of displacement), but “by the third and fourth years after the disaster, evacuees displaced [by these natural disasters] see a 0.18 standard deviation improvement in scores.” Sacerdote also finds that the improvements observed were “concentrated among students initially in the lowest quintiles of the test score distribution.” 1. Define the outcome (Y), the endogenous regressor (X), and the instrument (Z) in the context of this study.2. Is this instrument relevant? Explain why or why not.3. Is this instrument exogenous? Explain why or why not.4. For what group of individuals is this study externally valid? List at least two groups for which this study is unlikely to yield externally valid…

In a study of birth order and intelligence, IQ tests were given to 18- and 19-year-old men to estimate the size of the difference, if any, between the mean IQs of firstborn sons and secondborn sons. The following data for 10 firstborn sons and 10 secondborn sons are consistent with the means and standard deviations reported in the article. It is reasonable to assume that the samples come from populations that are approximately normal. Can you conclude that the mean IQ of firstborn sons is greater than the mean IQ of secondborn sons? Let μ1 denote the mean IQ of firstborn sons and μ2 denote the mean IQ of secondborn sons. Use the α = 0.01 level and the P-value method with the table. Firstborn 128 101 128 112 121 105 122 98 106 108 Secondborn 121 125 110 107 114 93 80 94 91 83 Part(a): State the appropriate null and alternate hypotheses. H0:   H1: This is a _____…