A sample of 20 elements selected from a population produced a mean of 65 and a standard deviation of 9. Another sample of 25 elements selected from another population produced a mean of 58 and a standard deviation of 11. Assume that the two populations are normally distributed and the standard deviations of the two populations are equal. The null hypothesis is that the means of the two populations are equal and the alternative hypothesis is that the means of the two populations are not equal. The significance level is 5%. The critical values of t are: a. –2.014 and 2.014 b. –2.017 and 2.017 c. –1.681 and 1.681 d. –1.679 and 1.679

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.

The mean tar content of a simple random sample of 25 unfiltered king-size cigarettes is 21.4 mg, with a standard deviation of 3 mg. The mean tar content of a simple random sample of 25 filtered 100-mm cigarettes is 13.0 mg with a standard deviation of 3.8 mg. The accompanying table shows the data. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Let population 1 be unfiltered king-size cigarettes. Complete parts (a) through (c) below. Click the icon to view the data. a. Use a 0.05 significance level to test the claim that unfiltered king-size cigarettes have a mean tar content greater than that of filtered 100-mm cigarettes. What does the result suggest about the effectiveness of cigarette filters? Identify the null and alternative hypotheses. O B. Ho: H1 =H2 O C. Ho: H1 #H2 H1: H1 =H2 O A. Ho: H1 = H2 H:H1 H2 O F. Ho: H1 = H2 H1:H1> H2 H:H1=H2 Hq: H1…

A professor is concerned that the two sections of college algebra that he teaches are not performing at the same level. To test his claim, he looks at the mean exam score for a random sample of students from each of his classes. In Class 1, the mean exam score for 13 students is 75.1 with a standard deviation of 5.8. In Class 2, the mean exam score for 16 students is 82.6 with a standard deviation of 7.3. Test the professor's claim at the 0.02 level of significance. Assume that both populations are approximately normal and that the population variances are equal. Let Class 1 be Population 1 and let Class 2 be Population 2. Step 2 of 3: Compute the value of the test statistic. Round your answer to three decimal places.

A researcher was interested in knowing if mean BMI was different between males and females. He obtained the following test results. Choose the correct interpretation of the results: F test p value = 0.30 Two sample t test, assume equal variance = 0.02 Two sample t test, assume unequal variance = 0.61 Mean BMI is not significantly different between males and females. None Mean BMI is higher in males than females. Mean BMI is significantly different between males and females.

A school psychologist was interested in whether students in the chess club scored above or below the mean grade point average (GPA) at her school. She calculated the overall average GPA at the school to be 2.55 with a standard deviation of 0.5 and noted that the distribution was approximately normal. She then figured the average for the 30 students in the chess club. Their mean GPA was 2.76. a. Using the five steps of hypothesis testing, was the group of 30 chess club students' GPA different from students in general at this school? (Use the .05 significance level.) Be sure to sketch the distributions involved. Be sure to fully state the five steps and show ALL calculations/work. b. Additionally, explain the logic of what you did to a person who understands hypothesis testing for studies in which the sample consists of a single individual but is unfamiliar with hypothesis testing involving a sample of more than one individual. (Be sure your explanation includes a discussion of the…

A basketball coach believes that the variance of the heights of adult male basketball players is different from the variance of heights for the general population of men. The sample variance of heights, measured in inches, for a random sample of 19 basketball players is 14.22. The sample variance for a random sample of 18 other men is 34.49. Assume that both population distributions are approximately normal and test the coach’s claim using a 0.10 level of significance. Does the evidence support the coach’s claim? Let male basketball players be Population 1 and men in general be Population 2.   Step 1 of 3:  State the null and alternative hypotheses for the test. Fill in the blank below. H0: σ21=σ22: Ha: σ21⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯σ22 Step 2 of 3:  Compute the value of the test statistic. Round your answer to four decimal places. Step 3 of 3:  Draw a conclusion and interpret the decision.

The salaries of professional baseball players are heavily skewed right with a mean of $3.2 million and a standard deviation of $2 million. The salaries of professional football players are also heavily skewed right with a mean of $1.9 million and a standard deviation of $1.5 million. A random sample of 40 baseball players’ salaries and 35 football players’ salaries is selected. The mean salary is determined for both samples. Let  represent the difference in the mean salaries for baseball and football players. Which of the following represents the shape of the sampling distribution for ? skewed right since the populations are both right skewed skewed right since the differences in salaries cannot be negative approximately Normal since both sample sizes are greater than 30 approximately Normal since the sum of the sample sizes is greater than 30