A. 285 +/- 8.17. B. 8.17. +/- 0.27. C. 288 +/- 8.17. 15. A class survey in a lar
ID: 3314799 • Letter: A
Question
A. 285 +/- 8.17.
B. 8.17. +/- 0.27.
C. 288 +/- 8.17.
15. A class survey in a large class for first-year college students asked, About how many hours do you study during a typical week? The mean response of the 463 students was x = 15.3 hours. Suppose that we know that the study time follows a Normal distribution with standard deviation = 8.5 hours in the population of all first-year students at this university. Step 1: Use the survey result to give a 99% confidence interval for the mean study time of all first-year students.
14.98 to 21.02
14.28 to 16.32
17.64 to 18.36
24.08 to 28.92
Step 2: What condition not yet mentioned is needed for your confidence interval to be valid? Normal distribution. Known . SRS. Unknown .
14. A class survey in a large class for first-year college students asked, "About how many hours do you study in a typical week?". The mean response of the 451 students was x¯¯¯x¯ = 16 hours. Suppose that we know that the study time follows a Normal distribution with standard deviation 8 hours in the population of all first-year students at this university.
What is the 99% confidence interval (±±0.001) for the population mean?
Confidence interval is from to hours.
12. The National Assessment of Educational Progress (NAEP) includes a mathematics test for eighth-grade students. Scores on the test range from 0 to 500. Suppose that you give the NAEP test to an SRS of 900 8th-graders from a large population in which the scores have mean = 285 and standard deviation = 125. The mean will vary if you take repeated samples.Suppose that an SRS of 900 8th-graders has = 288. Based on this sample, a 95% confidence interval for is
A. 285 +/- 8.17.
B. 8.17. +/- 0.27.
C. 288 +/- 8.17.
Explanation / Answer
Q12) Margin of error = (1.960*125)/SQRT(900) = 8.17
So, Option C is Correct
Q15) Margin of error = (2.5758*8.5)/SQRT(463) = 1.0175
(15.3-1.0175, 15.3+1.0175)
= (14.28, 16.32)
So, Option B is Correct
Q14) Margin of error = (2.5758*8)/SQRT(451) = 0.9703
(16-0.9703, 16+0.9703)
= (15.03 16.97)
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