Statistics Quiz

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Week6Quiz.docx

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1.

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An upper-level sociology class has 120 registered students: 34 seniors, 57 juniors, 22 sophomores, and 7 freshmen. Imagine that you choose one random student from the classroom (perhaps by using a random number table).Bottom of Form

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Question 1

2.5 Points

What is the probability that the student will be a junior?

1.

0.475

2.

0.57

3.

0.183

4.

0.283

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Question 2

2.5 Points

What is the probability that the student will be a freshman?

1.

0.475

2.

0.058

3.

0.283

4.

0.183

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Question 3

2.5 Points

If you are asked to select a proportionate stratified sample of size 30 from the classroom, stratified by class level (senior, junior, etc.), how many students from each group will there be in the sample?

1.

About 1 Freshmen, about 4 Sophomores, about 13 Juniors, about 9 Seniors

2.

About 3 Freshmen, about 7 Sophomores, about 15 Juniors, about 8 Seniors

3.

About 2 Freshmen, about 5 Sophomores, about 14 Juniors, about 8 Seniors

4.

About 3 Freshmen, about 7 Sophomores, about 15 Juniors, about 10 Seniors

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Question 4

2.5 Points

If you select a disproportionate sample of size 20 from the classroom, with equal numbers of students from each class level in the sample, how many freshmen will be in the sample?

1.

5

2.

7

3.

9

4.

6

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Question 5

2.5 Points

When taking a random sample from a very large population, how does the standard error of the mean change when the sample size is increased from 100 to 1,600?

1.

Smaller by a factor of 2

2.

Larger by a factor of 2

3.

Smaller by a factor of 4

4.

Larger by a factor of 4

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Question 6

2.5 Points

When taking a random sample from a very large population, how does the standard error of the mean change when the sample size is decreased from 300 to 150?

1.

Decreases by 1.41

2.

Increases by 1.41

3.

Decreases by 0.71

4.

Increases by 0.71

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Question 7

2.5 Points

When taking a random sample from a very large population, how does the standard error of the mean change when the sample size is multiplied by 4?

1.

Decreases by a factor of 4 

2.

Increases by a factor of 4

3.

Decreases by a factor of 2 

4.

Increases by a factor of 2

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The following information presents the number of parolees (per 100,000 people) for 12 of the most populous states as of July 2015.

State, Parolees (per 100,000 People)

California, 292

Texas, 556

New York, 288

Florida, 28

Illinois, 299

Pennsylvania, 1,035

Ohio, 193

Georgia, 334

Michigan, 239

North Carolina, 130

New Jersey, 214

Virginia, 27

Source: National Institute of Corrections, Correction Statistics by State, 2016

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Question 8

2.5 Points

Assume that σ = 226.83 for the entire population of 50 states. Calculate and interpret the standard error. (Consider the formula for the standard error. Since we provided the population standard deviation, calculating the standard error requires only minor calculations.) What is the standard error?

1.

68.45

2.

62.35

3.

64.58

4.

65.48

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