Note 1'8 Box and Whisker Plots

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Note 1.8 Box and Whisker Plots

• Our goal is to
• Read and create box and whisker plots

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Box and Whisker Plots

• Box and Whisker plots identify trends and
  summarize information.
• It divides the data into 4 equal parts
• The box represents 50 of the data
• The whiskers are each 25 of the data

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Steps to create a box and whisker plot

• Write the data in order from least to greatest.
• Find the number in the middle (the median) and
  draw a line through it.
• Find the median of the lower half and circle it.
  This is the Lower Quartile.
• Find the median of the upper half and circle it.
  This is the Upper Quartile.

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Example 1 Find the median, lower quartile and
upper quartile numbers for the data.

• 61, 28, 93, 42, 46, 58, 31, 24, 43, 46, 37
• Numbers in order ___________________________
• Median __________
• Lower Quartile ___________
• Upper Quartile ___________

• 8, 2, 3, 4, 2, 6, 6, 4, 5, 1, 1, 3
• Numbers in order ___________________________
• Median __________
• Lower Quartile ___________
• Upper Quartile ___________

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Example 2 Draw a Box and Whisker Plot

• Median 12
• Lower Quartile 5
• Upper Quartile 15
• Minimum 2
• Maximum 20

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Example 3 You Try! Draw a Box and Whisker Plot

• Median 10
• Lower Quartile 8
• Upper Quartile 12
• Minimum 0
• Maximum 15

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Example 4Answer the questions about the Box and
Whisker Plot

• The manager of a movie theater gathers data about
  the amount spent by each person when attending a
  movie in the evening.

• What is the least amount spent? ______
• What is the greatest amount spent? _____
• What is the median amount spent? ______
• What is the range? ________
• What is the range of the middle 50? __________

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Example 5 Answer the questions regarding the box
and whisker plot.
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Example 6 Create a box and whisker plot of the
data.

• Number of E-mail Messages Sent Each Week
• 5 19 20 15 16 18 24 22 21
• 24 40 18 9 18 24 23 25
• Numbers in order
• _________________________________________
• Min ______ Max ________
• Median _____ LQ _______ UP _______

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Homework 1.8

• Page 39-40 1-15 and 18