Measures of Central Tendency

Hello Class!

We have been working on our measures of central tendency, which is a fancy way of saying averages.  So far we have learned to calculate the mean, median, mode and range of a set of data and also to identify outliers. Please read the information below, watch the video and answer the questions by commenting on this post. Let's review.

Here are some scores from the last math test:  90, 98, 76, 64, 85, 90, 100, and 77

To calculate the MEAN:
Add up all of the numbers in the data set and divide by the number of numbers in the set.
      90 + 98 + 76 + 64 + 85 + 90 + 100 + 77 = 680
We have eight numbers in our data set so we will divide by 8
     680/ 8 = 85
The MEAN of our data set is 85

To calculate the MEDIAN:
Remember the median is the number that is in the middle of the data set, so you have to put the numbers in order from least to greatest.
     64, 76, 77, 85, 90, 90, 98, 100
In this data set, there are two numbers in the middle so to find the median, we must find the mean of the two middle numbers --> 85 + 90 = 175/2 = 87.5
The MEDIAN of our data is 87.5

To calculate the MODE:
The mode is the number that occurs most frequently in the data set.  In our data, every number appears once, except for 90 which appears twice.  Data can have one mode, two modes or no mode.
The MODE of our data is 90.

To calculate the RANGE:
Subtract the smallest number in the data set from the largest number in the data set.
     100 - 64 = 36
The RANGE of our data is 36

An OUTLIER is a number in the data set that is far away from all the other data.  Not every data set contains an outlier.

Mean, Median and Mode Video from SchoolTube



1. Does our data set have an outlier?
2. How could having an outlier affect the other measures?
3. Calculate the mean, median, mode and range for the following data set: 17, 38, 59, 12, 10, 47, 38, 19, 30