Quartiles for Grouped Data

Quartiles for Grouped Data

DP Year 2 - Math AI SL

Multiple Choice

Find the First Quartile of the following data set:

2, 3, 4, 5, 5, 5, 7

• 4

• 3

• 6

• 5

Multiple Choice

Find the Third Quartile of these numbers:

2, 3, 4, 5, 5, 5, 7

• 4

• 6

• 3

• 5

Multiple Choice

In the data set 33, 25, 42, 25, 31, 37, 46, 29, 38

What is the upper quartile of the data?

• 33

• 37

• 40

• 46

Multiple Choice

Find the lower quartile of the following set of scores.

12, 9, 4, 6, 5, 8, 9, 4, 10, 2

• 10

• 4

• 9

• 6

Multiple Choice

What is the middle number in a set of data?

• range

• median

• quartile 1

• quartile 3

Multiple Choice

True or False?

Quartiles are the values which divide the whole distribution into four equal parts.

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Q1 is the first quartile

Q2 is the second quartile

Q3 is the third quartile

• True

• False

​Finding the Quartile for Grouped Data

Multiple Choice

How do we find the quartiles for grouped data?

​Example 1

​​The following table gives the amount of time (in minutes) spent on the internet each evening by a group of 56 students.

a. Create a frequency distribution table.

b. Calculate Q1, Q2, and Q3.

c. Interpret the results.

Multiple Choice

What is the value of the second quartile?

• 17.1

• 18.1

• 17.5

• 18.5

Fill in the Blanks

Using the same set of data, find the upper quartile.

​USE of GDC

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Open Ended

​​The table shows the mathematics test scores of Grade 12 students.

Which data (red ink)  in the table are incorrect? Give your reason for each answer.

Multiple Choice

Use your GDC and compute for Q1, Q2, and Q3.

• Q1 = 28

  Q2 = 33

  Q3 = 38

• Q1 = 22

  Q2 = 30

  Q3 = 44

• Q1 = 29

  Q2 = 34

  Q3 = 39

• Q1 = 25

  Q2 = 40

  Q3 = 47

Multiple Choice

What does Q1 = 28 mean?

• 25% of the students got a score less than or equal to 28.

• 25% of the students got a score greater than or equal to 28.

• 75% of the students got a score less than or equal to 28.

• 75% of the students got a score greater than or equal to 28.

Fill in the Blanks

Use a GDC to calculate $Q_1$  , $Q_2$  , and $Q_3$   of the time spent (in minutes) to travel to work in the data set.

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Interpret the result for each quartile.

​Example 3

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​Be ready for a Quiz next meeting.

Kindly check the ManageBac for more details.

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​Don't forget to smile :-)

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​All the best!