Can someone please confirm that my answers are correct, and if they are not, why
ID: 3129170 • Letter: C
Question
Can someone please confirm that my answers are correct, and if they are not, why are they not? Thank you!!
7) Nitrogen oxide levels are not to exceed 0.9 grams per mile (g/ml). An administrator in a very large company is assigned to test whether the mean level of nitrogen oxides (NOX) emitted in the exhaust of a particular car model in their very large fleet of cars exceeds 0.9 grams per mile. He randomly samples 40 cars and finds x= 0.97. If = .15 g/ml grams, what is the value of the standardized z test statistic or z-score?
Select one:
a. 0.01
b. 0.07
c. 0.47
d. 2.53
e. 2.95
8) Referring to question 7, supposing the z = 1.69. What is the P-value for testing H0: = 0.9 versus Ha: > 0.9?
Select one:
a. 0.0169
b. 0.0314
c. 0.0455
d. 0.0910
e. 0.2667
f. 0.9545
9) Referring to questions 7 and 8, supposing the P-value = 0.0368, what should the administrator conclude at = 0.05?
Select one:
a. He should reject the null hypothesis and conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust exceeds 0.9 grams.
b. He should reject the null hypothesis and conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust is 0.9 grams.
c. He should fail to reject the null hypothesis and conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust exceeds 0.9 grams.
d. He should fail to reject the null hypothesis and say that she has insufficient evidence to conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust exceeds 0.9 grams.
e. He should fail to reject the null hypothesis and conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust is 0.9 grams.
10) When asked to explain the meaning of "the P-value was P = 0.03," a student says, "This means there is only a 0.03 probability that the null hypothesis is true." Is this a correct explanation?
Select one:
a. Yes, this is a correct explanation. It matches the definition of P-value well.
b. No, this is a false explanation. A P-value of 0.03 means that the outcome is at least 3% higher among one group than among the other group.
c. No, this is a false explanation. A P-value is the probability, assuming the null hypothesis is true, that the test statistic will take a value at least as extreme as that actually observed.
d. No, this is a false explanation. A P-value of 0.03 means that there is a probability of 0.03 that the null hypothesis is false.
e. No, this is a false explanation. A P-value of 0.03 means that there is a probability of 0.03 that the alternative hypothesis is false.
f. No, this is a false explanation. A P-value of 0.03 means that there is a probability of 0.03 that the alternative hypothesis is true.
11) The following situation applies to questions 11-15:
We suspect that on average students will score higher on their second attempt at the SAT mathematics exam than on their first attempt. Suppose we know that the changes in score (second try minus first try) have a standard deviation = 50. Here are the results for 46 randomly chosen high school students:
Variable: change–0 | 76655–0 | 444333333221111 0 | 000011222333 0 | 555666789 1 | 00223
PLAN: Plan to perform a test of significance on the population mean with known. Use = 0.05.
What are the appropriate hypotheses for this procedure?
Select one:
a. H0: x = 0 and Ha: x > 0
b. H0: x = 0 and Ha: x < 0
c. H0: x = 0 and Ha: x 0
d. H0: = 0 and Ha: > 0
e. H0: = 0 and Ha: < 0
f. H0: = 0 and Ha: 0
12) True or False: The parameter of interest is the mean change in SAT mathematics exam score (second try minus first try) of the random sample of 46 high school students.
Select one:
a. True
b. False
13) SOLVE step:
Can we say that the condition of "Normality of the Sampling Distribution of x" is met? Why or why not?
Select one:
a. Yes, because the sample size is large enough to apply the Central Limit Theorem.
b. No, because the sample size is to small to apply the Central Limit Theorem.
c. Yes, because the population of change in scores is Normal.
d. No, because we do not know if the population of change in scores is Normal.
14) The mean of the change in scores is x = 13.108696. Using this, find the P-value for this test.
Select one:
a. 0.0178
b. 0.0375
c. 0.2622
d. 0.9625
15) CONCLUDE step:
Suppose the P-value is 0.0271. What should we conclude? Use = 0.01.
Select one:
a. We should reject the null hypothesis and conclude that the mean change in the SAT mathematics exam is greater than 0.
b. We should reject the null hypothesis and conclude that the mean change in the SAT mathematics exam is 0.
c. We should fail to reject the null hypothesis and conclude that the mean change in the SAT mathematics exam is greater than 0.
d. We should fail to reject the null hypothesis and say that we have insufficient evidence to conclude that the mean change in the SAT mathematics exam is greater than 0.
e. We should fail to reject the null hypothesis and conclude the mean change in the SAT mathematics exam is 0.
Explanation / Answer
7) z 2.951459 8) p 0.91 9) a. He should reject the null hypothesis and conclude that the mean level of nitrogen oxides (NOX) emitted in the exhaust exceeds 0.9 grams 10) a. Yes, this is a correct explanation. It matches the definition of P-value well. 11) d. H0: = 0 and Ha: > 0 12) TRUE 13) a. Yes, because the sample size is large enough to apply the Central Limit Theorem. 14) 0.0375 15) d. We should fail to reject the null hypothesis and say that we have insufficient evidence to conclude that the mean change in the SAT mathematics exam is greater than 0.