Sunday
December 21, 2014

Homework Help: statistics

Posted by jeff on Saturday, January 9, 2010 at 9:34am.

Question 1
Question 1

1.
Question 1 text

The head of the History Department wants to compare the averages of 2 different instructor’s to see if they differ. A sample of 15 students in Instructor A’s class has average of 74 with a standard deviation of 11. A sample of 12 students in Instructor B’s class has a mean of 77 and a standard deviation of 13. Variances are assumed to be equal. What is the test value?
Answer
Question 1 answers
-0.65
-0.64
-0.62
-0.63

Question 2
Question 2

1.
Question 2 text

A two-tailed t-test independent samples is to be performed. The variances are assumed to be unequal. Group one has 17 people in the sample and group two has 14 people in the sample. If alpha = 0.05, what will be a correct critical value?
Answer
Question 2 answers
2.12
2.16
1.771
2.045

Question 3
Question 3

1.
Question 3 text

Which of the following would not be an example of dependent samples?
Answer
Question 3 answers
Students taking a pretest and a posttest on the same material
Patients are matched according to blood types in a hospital study
The salaries of truckers in Wyoming and compared to the salaries of truckers in Rhode Island.
The effect of a drug on reaction time measured by a before and after test.

Question 4
Question 4

1.
Question 4 text

Which of the following is not a requirement necessary to use the z-test in comparing two proportions?
Answer
Question 4 answers
the samples must be independent
Np must be 5 or more
Nq must be 5 or more
The samples must be dependent

Question 5
Question 5

1.
Question 5 text

The pooled estimate of the population variance for a given hypothesis test was 0.35. Sample 1 had 40 people out of 90 who liked poodles and sample 2 had 30 people who liked poodles. How many people were questioned in sample 2?
Answer
Question 5 answers
110
58
66
90

Question 6
Question 6

1.
Question 6 text

In a sample of 80 Honda cars, 45% of them got 28 miles per gallon,while a sample of 100 Nissan cars showed that 42% of them got 28 miles per gallon. If Honda cars are considered to be the first proportion,what would be the value of x1 ?
Answer
Question 6 answers
36
42
45
28

Question 7
Question 7

1.
Question 7 text

Using the z-test for comparing two independent means, sigma1 = 10, n1 = 32, sigma2 = 12 and n2 = 31, the standard error of difference would be:
Answer
Question 7 answers
7.77
2.79
0.7
0.836

Question 8
Question 8

1.
Question 8 text

A student was conducting a hypothesis test to compare 2 independent samples using the z-test. He is checking the claim that there is no difference between to different samples. Sample 1 had a mean of 85, a standard deviation of 14 and there were 36 items in he sample. Sample 2 had a standard deviation of 15 and there were 32 items in the sample. The student does not know what the mean of sample 2 was, but the test value was z= 1.85. What the mean of sample 2?
Answer
Question 8 answers
78.47
91.53
61.92
79.62

Question 9
Question 9

1.
Question 9 text

A hypothesis test will be performed to test the difference between means when the 2 samples are independent. Which test will be used when the population standard deviations are not known?
Answer
Question 9 answers
z-test
t-test
test of proportions
chi-square test

Question 10
Question 10

1.
Question 10 text

The t-test for independent samples when the variances are equal will be used to compare 2 means. One sample is size 12, the other sample is size 10. A two-tailed test will be performed using Alpha = 0.02. What would be a correct critical value for this test?
Answer
Question 10 answers
2.518
2.718
2.821
2.528

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