Details of Sophia Statistics Unit 4 Milestone Questions Answers Rationale Latest Summer 2021
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3 questions were answered incorrectly.
1
The table below shows the grade and reading level for 5 students.
Grade Reading Level
Student 1 2 6
Student 2 6 14
Student 3 5 12
Student 4 4 10
Student 5 1 4
For grade, the mean is 3.6 and the standard deviation is 2.1.
For reading level, the mean is 9.2 and the standard deviation is 4.1.
Using the formula below or Excel, find the correlation coefficient, r, for this set of students. Answer choices
are rounded to the nearest hundredth.
1.00
0.85
0.71
Sophia Statistics Unit 4 Milestone
RATIONALE
In order to get the correlation, we can use the formula:
Correlation can be quickly calculated by using Excel. Enter the values and use the function "=CORREL(".
CONCEPT
Correlation
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2
This scatterplot shows the maintenance expense for a truck based on its years of service.
The equation for least regression line to this data set is ŷ = 76.82x + 88.56.
What is the predicted value (in dollars) for maintenance expenses when a truck is 7 years old?
$549
$473
$626
$703
RATIONALE
In order to get the predicted maintenance expense when the age of the truck is 7 years, we simply substitute the value
7 in our equation for x. So we can note that:
CONCEPT
Predictions from Best-Fit Lines
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3
Raoul lives in Minneapolis and he is planning his spring break trip. He creates the scatterplot below to assess how
much his trip will cost.
Which answer choice correctly indicates the explanatory and response variables for the scatterplot?
Explanatory variable: Distance
Response variable: Cost
Explanatory variable: Minneapolis
Response variable: Miles flown
Explanatory variable: Miles flown
Response variable: Minneapolis
Explanatory variable: Cost
Response variable: Distance
RATIONALE
The explanatory variable is what is along the horizontal axis, which is distance. The response variable is along the
vertical axis, which is cost.
CONCEPT
Explanatory and Response Variables
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4
Which of the following scatterplots shows a correlation affected by an influential [Show Less]