Quartiles, IQR, and Standard Deviation

Quartiles, IQR, and Standard Deviation

Quartiles

​The values that divide a list of numbers into quarters

Use 1-Var Stats to find them

Find Q1, median, and Q3 using 1-Var Stats

20, 28, 32, 48, 52, 63, 99, 99

Multiple Choice

Determine the lower quartile:

47, 48, 48, 52, 74, 99

• 48

• 50

• 74

• 99

Multiple Choice

Determine the upper quartile:

42, 88, 74, 15, 34, 93, 87

• 34

• 74

• 88

• 93

Interquartile Range

Q3 - Q1 = IQR

​20, 28, 32, 48, 52, 63, 99, 99

Multiple Choice

Find the IQR:

42, 88, 74, 15, 34, 93, 87

• 54

• 88

• 15

• 34

Fill in the Blanks

Determine the IQR:

77, 77, 79, 92, 93, 97, 99

Box Plots

Visual representation of 5 number summary

What is the upper quartile?

Multiple Choice

The box plot summarizes the data for the average monthly high temperatures in degrees Fahrenheit for Orlando, Florida. The third quartile is...

• 92

• 90

• 83

• 71

Multiple Choice

What is the range of the box plot shown?

• 7

• 2

• 3

• 4

Standard Deviation

A measure of how spread out the data is

Find the population and sample standard deviation:

​20, 28, 32, 48, 52, 63, 99, 99

Fill in the Blanks

What is the population standard deviation (nearest tenth)?

5, 9, 7, 3, 3, 3

Fill in the Blanks

What is the sample standard deviation (nearest tenth)?

2, 6, 2, 5, 5, 9, 6