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MATH 1280 Introduction to Statistics

There are 16 questions on this quiz. You will see a small group of questions at a time.

Consider the following study: Marketing researchers Dominique and Huong wanted to know the following: “What percent of customers wear rain jackets at Seattle Food Store each day?” In an attempt to answer that question, Dominique and Huong designed a study. They called the store manager and arranged to collect data for 20 days. The researchers collected data for 4 hours each day for 20 days and counted the total number of shoppers who did and did not wear a rain jacket. The average number of customers per day who wore a rain jacket during the sample period was 32.

Question 1

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The population in this study was (read each answer and select the best one):

Select one:

a. All shoppers in Seattle.

b. All people who wear rain jackets.

c. All shoppers at the Seattle Food Store.

d. All shoppers at the Seattle Food Store during the study period.

e. The 32 people per day who wore rain jackets to the Seattle Food Store.

Question 2

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The sample in this survey was:

Select one:

a. Dominique and Huong.

b. The people who were observed shopping at the Seattle Food Store during the study.

c. The people who wear rain jackets.

d. The four hours per day that were studied.

e. The 32 people per day who wore rain jackets to the Seattle Food Store.

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How would you describe the possibility that the sample was biased (read all answers and select the best one):

Select one:

a. There is no bias because the sample was large.

b. There is no bias because the multiple days were sampled.

c. There could be bias because the selected days might not be representative of all the days (such as changing weather).

d. Not enough information to determine the answer.

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Use this information for the next four questions: Researchers wanted to know about a standardized test that was used across the country. To get an estimate of the answer, they collected data from two classrooms of students who completed the test.

Scores from Classroom A:

8, 6, 9, 9, 8, 7, 8, 9, 10, 8, 10, 5, 4, 10, 9, 9

Scores from Classroom B:

9, 8, 7, 8, 9, 10, 9, 10, 7, 8, 10, 9, 9, 4, 6, 3

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The set of all scores on the standardized test across the country is:

Select one:

a. a statistic

b. a parameter

c. the sample

d. the population

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When all the scores for the two classrooms are added and divided by the number of observations, the resulting value is a:

Select one:

a. a statistic

b. a parameter

c. the sample

d. the population

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What is the mean score in Group A?

Select one:

a. 8.4375

b. 8.3125

c. 8.0625

d. 8.375

e. 8.4375 / sqrt(n)

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Load data for Group B into an R object called B, then run this command:

barplot(table(B))

What does the bar on the right represent?

Select one:

a. Nine students received a score of 5 on the quiz.

b. One student received a score of 6 on the quiz.

c. Three students received a score of 7 on the quiz.

d. Four students received a score of 9 on the quiz.

e. Three students received a score of 10 on the quiz.

Eighty adults with gum disease were asked the number of times per day they flossed. The (incomplete) results are shown below:

# per day	Freq.	Rel. Freq	Cum. Rel. Freq
0	15	.1875
1	21	.2625
2	18	.2250
3			.7875
4	9		.9000
5	8		1.000

Fill in the blanks in the table and answer the next two question:

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The count of people who flossed three times per day is:

Select one:

a. 11

b. 18

c. 12

d. 9

e. can not be determined

Question 9

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The cumulative relative frequency of those who flossed 0 to 2 times per day is:

Select one:

a. .2250

b. .7875

c. .6750

d. .1875

e. 0.000

Use this information for the next six questions:

category <- c('a', 'g', 'd', 'a', 'd', 'g', 'g', 'd')

speed    <- c(60, 83.3, 71, 64.4, 75, 90, 87, 73)

Question 10

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The data type of the category object is:

Select one:

a. numeric

b. factor

c. complex

d. mixed

Question 11

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The data type of the speed object is:

Select one:

a. numeric

b. factor

c. complex

d. mixed

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What is the mean of the category object?

Select one:

a. 'a'

b. 'd'

c. 'g'

d. between 'd' and 'g'

e. none of the above

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What is the mean of speed (rounded to 1 decimal place)?

Select one:

a. 75.5

b. 90.0

c. 60.0

d. 74.0

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What is the sample standard deviation of the speed data (rounded to 1 decimal place)?

Select one:

a. 113.4

b. 74.5

c. 10.6

d. 90.0

Question 15

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What is the minimum value of the speed data:

Select one:

a. 15.1

b. 60.0

c. 74.0

d. 14.9

e. 30.0

Some researchers collected data on the number of pairs of shoes that students own. Five students owned seven pairs, two students owned no pairs, and various students owned between one and five pairs of shoes. See the data in the frequency table:

Shoes owned	0	1	2	3	4	5	7
Frequency	2	4	20	8	6	4	5

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What is the mean of the number of pairs of shoes that the students owned?

Select one:

a. 3.0

b. 3.1

c. 2.6

d. 2.9

e. 2.2

Answer 1