1. Mean, Median, and Mode
Course

2. Mean aka Average
The mean of a data set is the sum of the data items divided by the number of data items
𝑠𝑢𝑚 𝑜𝑓 𝑑𝑎𝑡𝑎 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑑𝑎𝑡𝑎 𝑖𝑡𝑒𝑚𝑠

3. Example of Mean Find mean of 74, 42, 62 ,18, 54
Add up all of the data items
= 255
How many items are there? 5
= = 51

4. Outliers
An outlier is a data item that is much higher or lower than the other data items.
An outlier can greatly affect the mean by raising it or lowering it

5. Example of Outlier Find outlier of 5 10 12 13 8 9 26 11 5 6
How does it affect the mean?

6. Outlier answer
Outlier is 26 because it is much higher than the other values
It raises the mean because it is much higher than the other values

7. Median
Median is the middle value of a data set when they are arranged in numerical order.
The median for an even number of data items is the mean of the 2 middle terms.

8. Find the median of… 1 5 2 10 3 4

9. Median answer Put the data from the table in order numerically |
Middle
How many data items did you begin with? 20
How many did you write down? (They had better be the same)
So where is the middle? -> Between the 10th and 11th numbers
Between 2 & 3. Take the mean of 2 & = 5 2 =2.5

10. Mode Mode is the item(s) that occurs most frequently.
Can have 1 mode, or multiple modes
Can have no mode if all data items appear the same number of times

11. Find the mode of…
Rose
rose
pansy
peony
daisy
orchid

12. Mode Answer
Make a table with tick marks to count the number of occurrences
Rose Pansy Peony Daisy Orchid
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Since Rose and Daisy both appeared the most (3 times) there are 2 modes
Rose and Daisy