Sophia Intro to Stats Unit 4 Milestone 4.For ten students, a teacher records the following scores of two assessments, Quiz 1 and Test.
Quiz 1 (x) Test (y)
15 20
12 15
10 12
14 18
10 10
8 13
6 12
15 10
16 18
13
...
Sophia Intro to Stats Unit 4 Milestone 4.For ten students, a teacher records the following scores of two assessments, Quiz 1 and Test.
Quiz 1 (x) Test (y)
15 20
12 15
10 12
14 18
10 10
8 13
6 12
15 10
16 18
13 15
Mean 11.9 14.3
Standard Deviation 3.3 3.5
The correlation of Quiz 1 and Test is 0.568.
Given the information below, what is the slope and y-intercept for the least-squares line of the Quiz 1 scores and Test scores? Answer choices are rounded to the
hundredths place.
Slope = 0.54
y-intercept = 1.71
Slope = 0.54
y-intercept = 1.22
Slope = 0.60
y-intercept = 7.16
Slope = 0.60
y-intercept = 1.22
RATIONALE
We first want to get the slope. We can use the formula:
To then get the intercept, we can solve for the y-intercept by using the following formula:
We know the slope, , and we can use the mean of x and the mean of y for the variables and to solve for the y-intercept, .
CONCEPT
Finding the Least-Squares Line
2
A bank manager declares, with help of a scatterplot, that the number of health insurances sold may have some association with the number of inches it snows.
How many policies were sold when it snowed 2 to 4 inches?
350
470
210
240
RATIONALE
In order to find the total number of policies between 2 and 4 inches, we must add the three values of 10 in that interval.
At 2 inches, there were 100 policies.
At 3 inches, there were 110 policies.
At 4 inches, there were 140 policies.
So the total is 100 + 110 + 140 = 350 policies.
CONCEPT
Scatterplot
3
Which of the following scatterplots shows an outlier in the y-direction?
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