U6S Review Day 2

Which of the following correlation coefficients represents the best fit line for data?

(hint: think about absolute value)

• -0.43

• 0.74

• 0.03

• -0.81

• -0.61

Answer explanation

Step 1: look for closest value to -1 and 1

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Closest value to -1 → -0.81

Closest value to 1 → 0.74

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Step 2: look at absolute values (this means to turn any negative into a positive)

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-0.81 → 0.81

0.74 → 0.74

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Step 3: pick higher absolute value decimal

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Best coefficient here is -0.81 (this had a higher absolute value)

Tags

CCSS.HSS.ID.C.8

The data gathered and recorded in the scatter plot represents the grams of fiber, y, as a function of calories, x, present in quarter-cup servings of different green leafy vegetables.

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Which statement below is true?

• There is a strong correlation between x and y; here x causes y.

• There is no association in the data; here x does not cause y.

• There is an association between x and y; here we do not know why there is an association

• There is a strong negative linear correlation between x and y; here y causes x

Answer explanation

Step 1: association?

There is a strongly negative linear association

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Step 2: explanation?

The question does not explain at all why the variables are related, so we cannot say x controls y, or that y controls x

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Answer is: "there is an association, but we do not have an explanation for why"

Tags

CCSS.HSS.ID.C.9

What is the shape of the histogram?

(bonus: what math language keyword is used to determine the direction of skew)

• skewed left

• skewed right

• symmetrical

• uniform

Answer explanation

This histogram is skewed left, because fewer shaded regions exist on left

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Math language uses the word "outliers" to define the direction of skew

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Skewed left because "fewer shaded regions" exist on left

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Skewed left because "outliers" exist on left

What is the shape of the histogram?

(bonus: what math language keyword is used to determine the direction of skew)

• skewed left

• skewed right

• symmetrical

• uniform

Answer explanation

This histogram is symmetric

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Math language uses the word "outliers" to define the direction of skew

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Symmetric because "outliers" not present in data

Which box-and-whisker has a larger spread?

(bonus: what determines if data has small spread or large spread)

• Team A

• Team B

• Cannot determine

Answer explanation

Both teams are skewed right

"Longer whiskers" on the right

"Outliers" on the right

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IQR (box region) is the best measure of spread for skewed data

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Team A has a larger spread (because larger IQR in blue)

Team B has a smaller spread (because smaller IQR in yellow)

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In summary, Team A has more outliers than Team B, which is why Team A has a larger spread (the shaded region in blue) and longer whisker

Tags

CCSS.6.SP.B.4

CCSS.HSS.ID.A.1

Data was collected on the number of siblings for students in one classroom. The results are shown on the table.

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What is the min and max value for the data?

(find without using Desmos)

Answer explanation

Min = 0

Max = 4

Range = Max - Min = 4 - 0 = 4

Data was collected on the number of siblings for students in one classroom. The results are shown on the table.

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What is the median value for the data?

(find without using Desmos)

Answer explanation

The table means we have the following numbers:

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0, 0, 0, 0

1, 1, 1, 1, 1, 1, 1, 1

6, 6, 6, 6, 6, 6

3, 3, 3

4

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If you eliminate the smallest and largest numbers, then you can find the median

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First, four numbers were eliminated on both sides (shaded in red)

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Next, 6 numbers were eliminated on both sides (shaded in green)

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The remaining numbers are the median (shaded in black)

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Median = 1

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We know have an approximate guess of how the box-and-whisker plot looks without using Desmos

Tags

CCSS.6.SP.B.5C

An executive at a car company wants to examine the relationship of cars sold, C, as a function of money the company spends on marketing, M. (data is represented as thousands on the x and y axis)

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How can we label the x and y axis?

Answer explanation

The phrase "as a function of" lets you know how to label the x and y axis

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In math it is understood that words before "as a function of" represent y, and those after represent x

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y = Car Sales (C)

x = Marketing Budget (M)

Tags

CCSS.HSF.LE.B.5

An executive at a car company wants to examine the relationship of cars sold, C, as a function of money the company spends on marketing, M. (data is represented as thousands on the x and y axis)

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What do we know about the line of best fit for the data without using Desmos? (think about variables for x and y, and value of y-intercept)

Answer explanation

y = mx + b

This is the equation for a line

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Look at the axis labels

y = Car Sales (C)

x = Marketing Budget (M)

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Instead of using y and x in the equation, we will use C and M

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C = mM + b

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m = slope = unknown

b = y-intercept = we can guess

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The y-intercept will be more than 20 but less than 30, so lets pretend it will be 25

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C = mM + 25

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Tags

CCSS.HSF.LE.B.5