The term "Average" is vague
Average could mean one of four things. The arithmetic mean, the median, midrange, or mode.
For this reason, it is better to specify which average you're talking about.
Mean
This is what people usually intend when they say "average"
Population Mean:
Sample Mean:
Frequency Distribution:
The mean of a frequency distribution is also the weighted mean.
Median
The data must be ranked (sorted in ascending order) first. The median is the number in the
middle.
To find the depth of the median, there are several formulas that could be used, the one that we
will use is:
Depth of median = 0.5 * (n + 1)
Raw Data
The median is the number in the "depth of the median" position. If the sample size is even, the
depth of the median will be a decimal  you need to find the midpoint between the numbers on
either side of the depth of the median.
Ungrouped Frequency Distribution
Find the cumulative frequencies for the data. The first value with a cumulative frequency greater
than depth of the median is the median. If the depth of the median is exactly 0.5 more than the
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 Spring '09
 Mean, Median, Mode, Mean

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