Q1, Q3, IQR

Q1, Q3, IQR

Steps to Find Q1, Q3, IQR

• Step 1 - Order the data from least to greatest

  Step 2 - Find the median of the data set

  Step 3 - To find the Q1, look at all the numbers to the left of the median value.  Find the number in the middle.

  Step 4 - To find the Q3, look at all the numbers to the right of the median value.  Find the number in the middle 

  Step 5 - To find the IQR, subtract Q3 - Q1

Basic Questions

Multiple Choice

First step for finding the median is to order the numbers from least to greatest?

• True

• False

Multiple Choice

IQR = Q3 - Q1

• True

• False

Multiple Choice

Q1 is the median (middle) of the lower half of the data values.

• True

• False

Multiple Choice

Q2 is the same as the ______

• Mean

• Median

• Mode

• Range

Multiple Choice

Quartiles break the data set into _____ equal parts each representing 25% of the data.

• 1

• 2

• 3

• 4

Practice Problems

Make sure you write your data in order from least to greatest before solving!

Multiple Choice

Find the median, first quartile, third quartile, and interquartile range of the data.

23, 33, 25, 16, 27, 43, 29, 40, 35

• Median: 29

  First Quartile: 24

  Third Quartile: 37.5

  IQR: 13.5

• Median: 27

  First Quartile: 25

  Third Quartile: 35

  IQR: 10

• Median: 29

  First Quartile: 25

  Third Quartile: 37.5

  IQR: 12.5

• Median: 27

  First Quartile: 24

  Third Quartile: 35

  IQR: 11

Multiple Choice

Find the median, first quartile, third quartile, and interquartile range of the data.

203, 183, 212, 181, 157, 204, 189, 190

• Median: 189

  First Quartile: 182

  Third Quartile: 203

  IQR: 21

• Median: 189.5

  First Quartile: 182

  Third Quartile: 203

  IQR: 21

• Median: 189

  First Quartile: 182

  Third Quartile: 203.5

  IQR: 21.5

• Median: 189.5

  First Quartile: 182

  Third Quartile: 203.5

  IQR: 21.5

Multiple Choice

Find the median, first quartile, third quartile, and interquartile range of the data.

32, 53, 72, 66, 47, 54, 49, 67, 71

• Median: 54

  First Quartile: 49

  Third Quartile: 67

  IQR: 18

• Median: 54

  First Quartile: 48

  Third Quartile: 69

  IQR: 21

• Median: 54

  First Quartile: 48

  Third Quartile: 69

  IQR: 22

• Median: 54

  First Quartile: 49

  Third Quartile: 69

  IQR: 20

Multiple Choice

What is the IQR of the following Data Set:

1, 3, 4, 5, 5, 7, 9

• Q1: 3

  Q2: 4

  Q3: 6

  IQR: 6 - 3 = 3

• Q1:3.5

  Q2: 5

  Q3: 8

  IQR: 8 - 3.5 = 4.5

• Q1: 3

  Q2: 5

  Q3: 7

  IQR: 7 - 3 = 4

Multiple Choice

What is the Q1, Q2, and Q3 of the following data set?

4, 5, 6, 8, 9, 10, 11

• Q1: 4

  Q2: 8

  Q3: 11

• Q1: 5

  Q2: 8

  Q3: 10

• Q1: 4

  Q2: 5

  Q3: 6