Scores on an English spelling test are determined for a sample of 16 5th graders both before and after they learn some new vocabulary tricks of the trade. In the population of difference scores it is know that students improve with an average of 3 points, with a standard deviation of 4 points, and that the distribution of the differences is approximately normal. What is the standard deviation of the sampling distribution of the sample mean difference in spelling scores?
a. 4
b. 0.25
c. 1
d. 0.75
Q. 2A Washington Post poll shows that concerns about housing payments have spiked despite some improvements in the overall economy. In all, 53 percent of the 900 American adults surveyed said they are very concerned or somewhat concerned about having the money to make their monthly payment. Let p represent the population proportion of all American adults who are very concerned or somewhat concerned about having the money to make their monthly payment. Which are the appropriate hypotheses to assess if a majority of American adults are worried about making their mortgage or rent payments?
a. H0: p = 0.50 versus Ha: p > 0.50
b. H0: p 0.50 versus Ha: p < 0.50
c. H0: p = 0.53 versus Ha: p > 0.53
d. H0: p = 0.50 versus Ha: p = 0.53
Q. 3Scores on an English spelling test are determined for a sample of 16 5th graders both before and after they learn some new vocabulary tricks of the trade. In the population of difference scores it is know that students improve with an average of 3 points, with a standard deviation of 4 points, and that the distribution of the differences is approximately normal. What is the expected value of the sample mean difference in spelling scores?
a. 16
b. 5
c. 3
d. 4
Q. 4The null and alternative hypotheses for p = proportion of students who buy at least 3 textbooks in a semester is given below: H0: p = 0.80 (or p 0.80) Ha: p > 0.80 The results of a study gave a p-value of 0.08 . The results of this study also stated that the study results were not statistically significant. What mistake could the researchers have made?
Q. 5In which of the following scenarios is a paired design not appropriate?
a. Comparison of the wear pattern on one's left shoe and one's right shoe.
b. Comparison of a cream and an ointment in the treatment of a rash, where the ointment is applied to half the rash and the cream to the other half.
c. Comparison of the average energy use of two brands of dishwashers.
d. Comparison of the accuracy of taking a person's temperature orally and in the ear, where each person's temperature is taken using both methods.
Q. 6The null and alternative hypotheses for p = proportion of students who buy at least 3 textbooks in a semester is given below: H0: p = 0.80 (or p 0.80) Ha: p > 0.80 The results of a study gave a p-value of 0.08 . The results of this study also stated that the study results were not statistically significant. State your conclusion.
Q. 7A large company is making all of its employees take a stress test. Test scores on this stress test follow a normal distribution with a mean score of 3 and a standard deviation of 0.9 . A random sample of 35 employees is to be taken. What is the probability that the sample mean stress score is lower than 2.75?
Q. 8The null and alternative hypotheses for p = proportion of students who buy at least 3 textbooks in a semester is given below: H0: p = 0.80 (or p 0.80) Ha: p > 0.80 The results of a study gave a p-value of 0.08 . The results of this study also stated that the study results were not statistically significant. Give an example of a significance level the researchers performing the study could have used.
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