AnswersFLEX - Math 4Unit Test

Unit Test — Unit test Answers

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1
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Review the table showing the height of a drooping rope in terms of horizontal distance from its left end.Horizontal Distance (ft)Height (ft)030.52.512.252232.253.52.543

A
a = 0.248, b = 0.994, c = 2.979
B
a = 0.248, b = 0.994, c = 2.979
C
a = 2.979, b = 0.994, c = 0.248
D
a = 2.979, b = 0.994, c = 0.248
E
a = 0.248, b = –0.994, c = 2.979
F
a = 0.248, b = –0.994, c = 2.979
G
a = 2.979, b = –0.994, c = 0.248
H
a = 2.979, b = –0.994, c = 0.248
2
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A popular social media platform has begun offering stock shares to the public. In the past 2 years, the price of the stock has generally increased. An investment specialist gathers data on the stock price during the past 2 years and creates an exponential model for estimating the stock price based on the number of weeks after the first public offering.

Question illustration
A
$2.27 because ŷ = 0.0022(95) + 2.0583 = 2.2673.
B
$9.65 because and e2.2673 = 9.6533.
Option B
C
$185.05 because and 102.2673 = 185.05.
Option C
D
$220.44 because and 102.3433 = 220.44
Option D
3

The weight (in pounds) and height (in inches) for a child were measured every few months over a two-year period. The results are given in the table.

Question illustration
A
The slope is 1.98, which means for each additional inch in height, the child’s weight will increase by 1.98 pounds.
B
The slope is 1.98, which means for each additional inch in height, the child’s weight is predicted to increase by 1.98 pounds.
C
The slope is 0.50, which means for each additional pound in weight, the child’s height will increase by 0.5 inches.
D
The slope is 0.50, which means for each additional pound in weight, the child’s height is predicted to increase by 0.5 inches.
4

Athletes at the 2018 World Figure Skating Championships are evaluated in two rounds of competition: the Short Program, and the Free Skate. The sum of the scores for each skater are then used to determine the medalists. For each of the 24 male skaters at the 2018 World Championship, the scores for each round are displayed in a scatterplot.

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A
A linear model is appropriate because the residuals are centered about zero.
B
A linear model is not appropriate because there are outliers in the scatterplot.
C
A linear model is not appropriate because the residual plot does not show a linear pattern.
D
A linear model is appropriate because the scatterplot is roughly linear, and the residual plot does not show a clear pattern.
5

The scatterplot illustrates the relationship between two quantitative variables: the number of seeds planted per square foot and the yield of the crop (in pounds per square foot).

Question illustration
A
The more seeds that are planted per square foot, the smaller the expected yield of the crop.
B
The more seeds that are planted per square foot, the larger the expected yield of the crop.
C
The expected yield of a crop is high whenever the number of seeds planted per square foot is small or large. A larger yield is expected when the number of seeds per square foot is around 60.
D
The expected yield of a crop is low whenever the number of seeds planted per square foot is small or large. A larger yield is expected when the number of seeds per square foot is around 60.
6

The pH level of a substance can be determined by the formula pH = –log[H+], where [H+] is the hydrogen ion concentration in moles per liter. An alkaline substance has a pH level between 7 and 14. Which ion concentration corresponds to an alkaline substance?

A
3.5 x 10–16
B
5.0 x 10–12
C
1.0 x 10–7
D
1.1 x 10–4
7

The arm span and foot length were measured (in centimeters) for each of the 19 students in a statistics class and displayed in the scatterplot. An analysis was completed and the computer output is shown. PredictorCoefSE Coeft-ratiopConstant-7.6112.5672.9650.046Arm span0.1860.0355.3770.000S = 1.61R-Sq = 63.0%R-Sq(Adj) = 62.7%

Question illustration
A
0.630
B
0.649
C
0.794
D
0.806
8

The owner of a used car dealership is trying to determine if there is a relationship between the price of a used car and the number of miles it has been driven. The owner collects data for 25 cars of the same model with different mileage and determines each car’s price using a used car website. The analysis is given in the computer output.Using the computer output, what is the value of the coefficient of determination?

Question illustration
A
0.46
B
0.68
C
0.70
D
0.82
9

The loudness of a lawnmower is measured in decibels, modeled by the formula . What does 90 represent?

Question illustration
A
the initial loudness of the lawnmower
B
how loud the sound of the lawnmower is
C
the intensity of the sound of the lawnmower
D
the intensity of the sound of the lawnmower compared to the intensity of sound that is barely audible
10

A sports statistician was interested in the relationship between game attendance (in thousands) and the number of wins for baseball teams. Information was collected on several teams and was used to obtain the regression equation ŷ = 4.9x + 15.2, where x represents attendance (in thousands) and ŷ is the predicted number of wins. Which statement best describes the meaning of the slope of the regression line?

A
For each increase in attendance by 1,000, the predicted number of wins increases by 4.9.
B
For each increase in attendance by 1,000, the predicted number of wins increases by 15.2.
C
For each increase in the number of wins by 1, the predicted attendance increases by 4,900.
D
For each increase in the number of wins by 1, the predicted attendance increases by 15,200.
11

A sports analyst determines that the number of points scored in a basketball game is related to the number of shots taken during the game. The least-squares regression line is ŷ = 5.0 + 1.2x, where ŷ is the predicted number of points scored and x is the number of shots taken.

A
45
B
55
C
65
D
75
12

A newspaper collected information on schools in its circulation area in order to compare their quality. Two measures the newspaper collected for each school, mean class size and mean score on a statewide reading exam, are shown in the scatterplot. One school in the report, Springside Elementary, is labeled in the graph.

Question illustration
A
Springside does not affect the correlation.
B
Springside weakens the correlation shown in the scatterplot.
C
Springside strengthens the correlation shown in the scatterplot.
D
Removing Springside would increase the value of the correlation coefficient.
13

The scatterplot illustrates the relationship between distance and success rate of field-goal attempts for a sample of football kickers.

Question illustration
A
The kickers have unusually low success rates when the distance is large.
B
The kickers have unusually high success rates when the distance is small.
C
The kickers have higher success rates for longer field-goal attempts.
D
The kickers have lower success rates for longer field-goal attempts.
14

The population of a city, y, in thousands of people, measured x years after 1800 can be modeled by the regression equation y = . Which statement best interprets a value in the equation?

Question illustration
A
The city population in 1800 was 187,600 people.
B
The city population grows by 29,400 people per year.
C
The limiting value of the city population is 29,400 people.
D
The limiting value of the city population is 187,600 people.
15

A sports statistician was interested in the relationship between game attendance (in thousands) and the number of wins for baseball teams. Information was collected on several teams and was used to obtain the regression equation ŷ = 4.9x + 15.2, where x represents the attendance (in thousands) and ŷ is the predicted number of wins. What is the predicted number of wins for a team that has an attendance of 2,100?

A
25.49 wins
B
31.92 wins
C
36.82 wins
D
10,305.2 wins
16

A certain standardized test measures students’ knowledge in English and math. The English and math scores for 10 randomly selected students were recorded and analyzed. The results are shown in the computer output.Which of the following represents the standard deviation of the residuals?

Question illustration
A
1.223
B
34.55
C
78.712
D
124.13
17

Janice is considering buying a new home. She wants to estimate the monthly utilities (heating and air conditioning). She figures that the utilities are dependent on the size (square footage) of the home. She collects data on 10 homes in the neighborhood and finds a linear model to give the relationship between the size of the home and the monthly utilities. The equation of the line is ŷ = –8.1 + 1.91x, where ŷ is the mean monthly cost in utilities and x is the square footage of the home. The residual plot is shown.

Question illustration
A
No, there is no clear pattern in the residual plot.
B
Yes, there is no clear pattern in the residual plot.
C
No, there are no homes between 2,300 and 2,900 square feet.
D
Yes, half of the residuals are positive and half are negative.
18

A nutritionist collects data from 25 popular breakfast cereals. For each cereal, the number of calories per serving is plotted on the x-axis against the number of milligrams of sodium on the y-axis. The value of r for the resulting scatterplot is 0.83. How would the value of the correlation coefficient, r, change if sodium was plotted on the x-axis and calories plotted on the y-axis?

A
The value of r would increase.
B
The value of r would not change.
C
The value of r would change to –0.83.
D
The value of r could increase or decrease, depending of the strength of the new relationship.
19

Based on data taken from airline fares and distances flown, it is determined that the equation of the least-squares regression line is ŷ = 102.50 + 0.65x, where ŷ is the predicted fare and x is the distance, in miles.

A
$102.50
B
$435.00
C
$225.00
D
$330.00
20

College administrators at a small, private college noticed that students who had higher high school GPAs tend to have higher college GPAs.

A
Explanatory variable: size of collegeResponse variable: college GPA
B
Explanatory variable: high school GPAResponse variable: college GPA
C
Explanatory variable: college GPAResponse variable: high school GPA
D
Explanatory variable: type of college (private vs. public)Response variable: college GPA

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Unit Test — Unit test Answers — FLEX - Math 4