Study Document
Offline During the Final Exam A-Level Coursework
Pages:7 (2030 words)
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Document Type:A-Level Coursework
Document:#94105956
The fact that the sampling distribution of sample means can be approximated by a normal probability distribution whenever the sample size is large is based on the a. central limit theorem
B. fact that we have tables of areas for the normal distribution
C. assumption that the population has a normal distribution
D. None of these alternatives is correct.
Answer: A- central limit theorem
Use the following situation for Questions 21-23. In order to estimate the average time spent on the dialysis machines per kidney patient at a local university hospital, data were collected for a sample of 81 patients over a one week period. Assume the population standard deviation is 1.2 hours.
21. The standard error of the mean is
A. 7.5 B. 0.014 C. 0.160 D. 0.133
M =Standard error of the mean =where N. is the sample size and ? is the sample deviation.
1.2/9
=0.133
Answer: D. 0.133
22. With a 0.95 probability, the margin of error is approximately
A. 0.26 B. 1.96 C. 0.21 D. 1.64
Answer: A. 0.26
23. If the sample mean is 9 hours, then the 95% confidence interval is
A.
7.04 to 110.96 hours
B.
7.36 to 10.64 hours
C.
7.80 to 10.20 hours
D.
8.74 to 9.26 hours
Answer:D
24. the't distribution is applicable whenever:
A. The sample is considered large (n ? 30).
B. The population is normal and the sample standard deviation is used to estimate the population standard deviation
C. n ? 100
D. n ? 1000
ANSWER:
b
Use the following situation for Questions 25 -- 26.
A random sample of 16
statistics examinations from a large population was taken. The average score in the sample was 78.6 with a variance of 64. We are interested in determining
whether the average grade of the population is significantly more than 75. Assume the distribution of the population of grades is normal.
25.
The test statistic is: A. 0.45
B. 1.80
C. 3.6
D. 8 Answer: b
26. At 95% confidence, it can be concluded that the average grade of the population
A. is not significantly greater than 75
B. is significantly greater than 75
C. is not significantly greater than 78.6
D. is significantly greater than 78.6
Answer: b
27. Independent samples are obtained from two normal populations with equal variances in order to construct a confidence interval estimate for the difference between the population means. If the first sample contains 16 items and the second sample contains 36 items, the correct form to use for the sampling distribution is the a. normal distribution
B. t distribution with 15 degrees of freedom
C. t distribution with 35 degrees of freedom
D. t distribution with 50 degrees of freedom
Degree of freedom is calculated as follows=n1 + n2 ? 2 = 16+36-2 = 50
Answer: D.t distribution with 50 degrees of freedom
Use the following situation for Questions 28 -- 33. A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A
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