What Do You Expect? MEAN, MEDIAN, MODE

Average Salary? What do you expect the average employee at McDonald’s makes?

Average Salary? What do you expect the average surgical tech makes? About $20/hr How about the average surgeon? A general surgeon makes about $250,000/yr. Specialists can make much more.

Average Price? What do you expect the average price for a car is at this dealership? A lot! About $ thousand.

Average Price? What do you expect the average price for a car is at this dealership? Probably not too much. Maybe around $1000 or less???

What is “average”? “Average” is the everyday word we use to describe what we expect to find in a given situation. Does anyone remember the formula for finding “average”? Add all items and divide by the total. Ages in this 1 st -2nd grade class: 6, 6, 6, 5, 7, 7, 5, 7, 7, 6 What is the average age? 62 ÷ 10 – 6.2 years old

What happens to expected results when unexpected things occur ? What about this classroom? Do you think the average age is still 6 ½ years old? Let’s check. Let’s take the same class and add in the “new student”: 6, 6, 6, 5, 7, 7, 5, 7, 7, = 92 ÷ 11 = 8.36 Are most students in this classroom a little more than 8 years old? To skew data: when something happens to distort the expected results.

Average: Mean, Median, Mode In real life, unexpected things happen, so in math, the everyday word “average” is broken down into 3 different calculations that each give a specific type of information. If we look at them all together they begin to give a more complete picture of what to expect. Mean: the traditional “average”. Add all items and divide by the number of items. Median: the exact middle. Line up the numbers in order and find the exact middle. If there is no exact middle, average the two middle numbers. Mode: the most common. There can be more than one mode, or no mode. In math, mean, median, and mode are called “measures of central tendency”.

Let’s Practice Julie gave a test that was worth 20 points. Here were the scores for 10 students. Calculate the mean, median, mode. 5, 8, 15, 18, 6, 20, 10, 13, 18, 15 Mean: Add all scores = 128 divided by 10 = 12.8 Median: Line up numbers in order and find exact center 5, 6, 8, 10, 13, 15, 15, 18, 18, is exactly in the middle Mode: 15 and 18 are the most common

Wrap-Up In each situation, what factors might skew the simple average? Would it benefit to get a complete picture of “average” by calculating mean, median, and mode? Average height of students in class where one student is a tall girl on the basketball team Average salary of all of people working in a business Average income of all people in the United States