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Practice Exam Answers

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1
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Which of the following boxplots correctly displays the distribution of quiz grades?

A
Image with description A boxplot. A number line labeled quiz grades goes from 12 to 30. The whiskers range from 12 to 30, and the box ranges from 18 to 27. A line divides the box at 24.
B
Image with description A boxplot. A number line labeled quiz grades goes from 12 to 30. Points are at 12, 14, 15, and 16. The whiskers range from 20 to 30, and the box ranges from 23 to 27. A line divides the box at 25.
C
Image with description A boxplot. A number line labeled quiz grades goes from 12 to 30. The whiskers range from 12 to 30, and the box ranges from 23 to 27. A line divides the box at 25.
D
Image with description A boxplot. A number line labeled quiz grades goes from 12 to 30. Points are at 12 and 14. The whiskers range from 15 to 30, and the box ranges from 22 to 27. A line divides the box at 25.
2
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What percentage of eighth-grade students walked more than six miles?

A
50 percent
B
20 percent
C
30 percent
D
15 percent
3

What is the probability that a randomly selected participant dreams in color but not in black and white?

A
0 point 1 0
B
0 point 1 1
C
0 point 0 2
D
0 point 0 5
4

Suppose a traveler is selected from this sample at random. Let event cap A is equal to home sharing and event cap b is equal to fly. Are events cap A and cap b independent?

A
No, cap p times cap A is not equal to cap p times open paren cap b divides cap A close paren .
B
Yes, cap p times cap A is equal to cap p times open paren cap A divides cap b close paren .
C
Yes, cap p times cap A is not equal to cap p times open paren cap b divides cap A close paren .
D
No, cap p times cap A is equal to cap p times open paren cap A divides cap b close paren .
5

How many unique random numbers need to be selected from the table of random digits?

A
40
B
80
C
120
D
3
6

What is the value of the missing probabilities?

A
0 point 2 5
B
0 point 2 0
C
0 point 6 0
D
0 point 1 5
7

Using technology, what is the y -intercept and what is its interpretation?

A
The y -intercept is negative 34 point 1 3 . When the weight is 0 pounds, the height will be negative 34 point 1 3 inches.
B
The y -intercept is 17 point 3 7 . When the weight is 0 pounds, the height will be 17 point 3 7 inches.
C
The y -intercept is negative 34 point 1 3 . When the weight is 0 pounds, the height is predicted to be negative 34 point 1 3 inches.
D
The y -intercept is 17 point 3 7 . When the weight is 0 pounds, it does not make sense to interpret the height.
8

Which of the following is a true statement regarding the information shown in the pie chart?

A
Side dish choice is a discrete variable.
B
Side dish choice is a continuous variable.
C
Side dish choice is a categorical variable.
D
Side dish choice is a quantitative variable.
9

Based on the scatterplot and residual plot, which type of model is most suitable for modeling electric bills based on mean monthly temperature?

A
A linear model is appropriate because the residual plot shows a random scatter.
B
An exponential model is appropriate because the scatterplot of log temperature and log bill is roughly linear.
C
A power model is appropriate because the scatterplot of log temperature and log bill is roughly linear, and the residual plot shows no distinct pattern.
D
A logarithmic model is appropriate because logarithms were used to transform the data sets.
10

What is the probability that a randomly selected customer purchases the ultimate car wash if they vacuum their car?

A
0 point 1 2
B
0 point 4 8
C
0 point 3 2
D
0 point 2 0
11

Which of the following best describes the center and variability of the distribution?

A
The scores on the test are centered around 66 and vary from 40 to 80.
B
The scores on the test are centered around 63 and vary from 45 to 85.
C
The scores on the test are centered around 69 and vary from 45 to 85.
D
The scores on the test are centered around 66 and vary from 43 to 85.
12

The relationship in the scatterplot is

A
weak because it contains unusual points.
B
weak, positive, and linear.
C
positive and linear with no unusual points.
D
strong, negative, and linear.
13

Which statement best describes how the circled point influences the correlation shown in the scatterplot?

A
Because the point follows the linear trend, the correlation does not change.
B
Because the point lies above the linear trend, it strengthens the correlation.
C
Because the point lies outside the linear trend, it strengthens the correlation.
D
Because the point lies outside the linear trend, it weakens the correlation.
14

A farmer sows 100 seeds of a new type of corn and wants to quickly determine the yield, or total number of ears of corn, for the crop when it has matured. He decides to take a simple random sample of the crop by using a random digit table. What is the fewest number of digits that should be used, given that there are 100 plants in total?

A
2
B
4
C
3
D
1
15

Kaitlyn and Allison took a standardized algebra test in different states. Kaitlyn took the test for Virginia and scores a 458 Allison took the test for North Carolina and scored a 185 Suppose the mean and standard deviation for the algebra scores for Virginia were 405 and 30 , respectively, and the mean and standard deviation for the algebra scores for North Carolina were 152 and 20 , respectively. Which student did better on her algebra test?

A
Allison did better since her z -score is higher than Kaitlyn’s z -score.
B
Kaitlyn did better since her z -score is higher than Allison’s z -score.
C
Allison did better since her z -score is closer to the mean than Kaitlyn’s z -score.
D
Kaitlyn and Allison did equally well since their scores are both above the mean.
16

A tire company wants to determine if tires made with a new type of tread will last longer than tires made with the original type of tread. The company has access to 20 different vehicles and wants to use a randomized block design for the experiment. Which of the following variables would be the best to block the experimental units?

A
year of vehicle
B
color of the vehicle
C
type of vehicle
D
make of the vehicle
17

Market researchers were interested in the relationship between the price of bobbleheads and the demand of bobbleheads. Information was collected from a market research survey and was used to obtain the regression equation widehat y is equal to negative 0 point 2 2 7 x plus 50 point 4 5 5 , where x represents the price of a bobblehead (measured in dollars) and widehat y is the predicted demand of bobbleheads (in units). What is the predicted demand of a bobblehead that has price of 29 point 9 9 dollars ?

A
90 point 1 5 4 units
B
43 point 6 4 7 2 7 units
C
50 point 4 5 5 units
D
negative 6 point 8 0 7 7 3 units
18

Which of the following is not true about cluster sampling?

A
Cluster sampling uses randomly selected clusters and samples everyone within each cluster.
B
Cluster sampling has the advantage of reducing sampling variability.
C
Cluster sampling uses clusters, which are miniature, nonoverlapping versions of the population.
D
Cluster sampling has the advantage of saving time and money.
19

Many large cities have considered or passed proposals that ban the use of plastic grocery bags in stores. A concerned student would like to measure if residents of her hometown would consider a similar ban on plastic bags. Standing in a busy shopping area, the student approaches adults and asks, "Items made of plastics are a dangerous, growing source of pollution to our world’s oceans and threaten many animal species. Given this, would you support a ban on plastic shopping bags in our city stores?” Which type of bias is most likely to be present in the survey results?

A
This is response bias because some adults may not provide truthful answers to the plastic bag question.
B
This is nonresponse bias because many adults chosen may decline to answer questions about the environment.
C
This is voluntary response bias because many adults may be eager to share their opinions about plastic grocery bags.
D
This is question wording bias because the survey question attempts to influence subjects’ responses.
20

Vehicles passing over a bridge have two options for paying their bridge toll: paying with a live cashier or using a Speed Pass device affixed to the dashboard. Data on a busy day for cars and trucks passing over the bridge are shown here. Payment Method Live Cashier Speed Pass Total Vehicle Type Car 35 67 102 Truck 18 47 65 Total 53 114 167 What percentage of vehicles are trucks, given that they use Speed Pass? Round the answer to four decimal places.

A
28 point 1 percent
B
72 point 3 percent
C
68 point 3 percent
D
41 point 2 percent

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