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Mean: The Average
Mean is the average number in your data.
Let’s say that these are the numbers in your
data:
1 2 3 4 5 6 7 8 9 10
2, 6, 14, 2, 5, 8, 9, 4, 7, 3
To calculate the mean, first add up all
of the numbers.
2
6
14
2
5
8
9
4
7
+ 3
60
Next, divide the sum by the number
of numbers in the data set.
There are ten numbers in the set.
So, 60 ÷ 10 =
6
The mean of your data set is 6.
Median: The Middle Number
In order to find the median of a data set,
you must rewrite the numbers in numerical
order.
Let’s use the same data set.
2, 6, 14, 2, 5, 8, 9, 4, 7, 3
Rewrite the set into numerical order.
2, 2, 3, 4, 5, 6, 7, 8, 9, 14
Cross out one number at a time alternating the
left side then the right side. The number that
can’t be crossed out is the median.
5
+6
11
11 ÷ 2 = 5.5
Wait, there looks like there’s a problem.
There is an even number of data so there
are two numbers left in the middle. If this
happens find the average of those two
numbers, that is the median.
The median is
5.5!
Mode: The Number that Appears Most
Often
This one is simple. Look at your list of data
2, 6, 14,
2, 5, 8, 9,
4, 7, 3
What number appears most in the data?
2 appears twice and that is more than any of
the other numbers. So the mode of your data
set is 2.
Range: The Domain of Data
In order to find the range, subtract
the minimum value of data from the
maximum value.
14
2
12
2, 6, 14, 2, 5, 8, 9, 4, 7, 3
In our data, the minimum is 2
and the maximum is 14.
The range of the data
is 12!
The Line Graph
One way to view the data you’ve collected
is in a line graph.
X
X
0
2
X
X
4
Place an X on the line for each
number in your data set.
X
X
6
X
2, 6, 14, 2, 5, 8, 9, 4, 7, 3
X
8
X
X
10
12
14
16
The line graph is helpful for visualizing
the mean, median, and mode.