Ch. 12 Vocabulary
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15.) quartile
16.) Interquartile range
17.) Box and whisker plot
18.) percentile
19.) percentile rank
12-4 Box & Whisker Plots
Algebra 1
Hints for making a
box-and-whiskers plot:
• Make sure data is in order from least to
greatest.
• Find the minimum value, median, maximum
value, upper & lower quartiles information
first.
• Plot the points for this info below a number
line.
• Then, draw box and whiskers.
Ex. 1 –Find the min., 1st Q, Median, 3rd
Q, and max. of each data set.
• Ex. 1)
• 17, 24, 25, 30, 33, 34, 36, 37, 39, 40, 40, 42, 48
• Draw the box and whiskers.
Box-and-whisker plots
Box
Whisker
0
10
20
30
Minimum
value (17)
Lower Quartile –
median of all
numbers in the list
to the left of the
median
(25+30)/2 = 27.5
40
Median
(36)
Whisker
50
Maximum
value (48)
Upper Quartile –
median of all numbers
to the right of the
median
(40+40)/2 = 40
Percentiles of a box & whisker plot
Percentiles – separate data sets into 100
equal parts
Ex. 2) Find the information
7, 8, 9, 10, 12, 14, 15, 16
Finding a percentile rank
• Percentile rank of a data value is the
percentage of data values that are less than or
equal to that value.
Ex. 3
• Of 25 test scores, fifteen scores are less than
or equal to 85. What is the percentile rank of
85?