Activity

Add the numbers of the data set together and divide by the number of data points .
During the first half, Harvey ran the following number of yards for his 5 carries:
9 11 16 4 10 Data points
What is the average (mean) number of yards per carry that
Harvey ran in the first half?
9 + 11+ 16 + 4 + 10 =
5
10

A Closer Look at Averages (Means) . . .
Agree
The person’s temperature is fine.
Disagree

A Closer Look at Averages (Means) . . .
500 Guests
How would you determine the average(mean) wealth of the guests staying at the Ritz Hotel on a particular day?
Would the average(mean) be affected if Bill Gates stayed at the hotel?
62.7 Billion

Comparison of Averages(Means) with an Extreme Value
500 guests - each having a wealth of
$1,000,000
Mean:
$1,000,000
499 Guests each having a wealth of
$1,000,000 and Bill
Gates having a wealth of $62.7 Billion
62,700,000,000
499,000,000
63,199,000,000
Mean:
$126,398,000

Sort
1
2
The middle number (in a sorted list of numbers).
Example: Cost of Dinners at a Restaurant:
13 15 18 21 11 12 10
Middle
10 11 12 13 15 18 21
Middle
What does the median cost of dinners tell us?

The restaurant adds a new dinner item to the menu:
10 11 12 13 14 15 18 21
Middle
If the number of data points is odd, the median is the mean (the average) of the middle two values: 13+14 = 13.5
2
• The median does not have to be a value in the dataset.
• The position of the median can be found by:
(the number of data points + 1) ÷ 2

What is the median points scored in the Falcons 2013 regular season?
40 27 27 30 24 23 30 19 27 23 24 23 20 34 31 17
17 19 20 23 23 23 24 24 27 27 27 30 30 31 34 40
Median: 25.5
• Sort
• Find position of middle value(s): (Number data points + 1)
2
• If necessary, average middle values

The mode is the number repeated most often.
Example:
What is the mode of the points scored in the Falcons 2013 regular season?
40 27 27 30 24 23 30 19 27 23 24 23 20 34 31 17
Do you think a data set could have more than one mode?
Do you think every data set has a mode?

1. Calculate the mean, median, and mode of purchasing the original 6 toys.
2. Make predictions about whether the purchase or return of toys will cause the measures of central tendency to increase or decrease.
3. Calculate the mean, median, and mode of the purchased/returned toys.
4. Discuss . Do the results match your predictions?