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Key
Idea
A
single number
can
be used to
describe
what is
typical
about a set
of
data.
Vocabulary
•
average
•
range (p. 271)
•
median
•
mean
•
mode
Materials
•
calculator |
Mean, Median, and Mode |
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How can data
be described by a
single number? |
| For 7 days in a
row Geneva recorded the following number of visits
to the school website: |
4, 2, 8, 9, 4,
10, 5 |
| She
used tiles to help find a single number
to describe the typical
or average
number of visits per day. |
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| The
mean
is often called the average. To find
the mean, add all the data and divide
by the number of data. |
4
+ 2 + 8 + 9 + 4 +
10 + 5 = 42 |
| 42
÷ 7 = 6 |
| The
mean is 6. |
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| The
median
is the middle number. To find the median,
arrange the data in order from least to
greatest. |
| 2, 4, 4, 5,
8, 9, 10 |
middle |
| The median is 5. |
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The
mode
is the data
value that occurs most
often. |
2, 4,
4, 5, 8, 9, 10
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| The mode is 4. |
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Sometimes
the median does not appear in the set of
values
because there is an even number of
values. Find the median for
the following data: 3, 1, 9, 6, 4,
1. |
| Arrange
the values in order from least to greatest. |
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1,
1, 3, 4, 6, 9 |
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middle |
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| Find
a number halfway between 3 and 4. Add the
two middle numbers and divide by 2.
Since 3 + 4 = 7 and 7 ÷ 2 = 3.5,
the median is 3.5. |
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