1. Data Analysis – Mean, Median, and Mode Mean, median and mode are different methods used to evaluate sets of data

2. Mean/Average Mean is usually the most difficult to calculate – The “mean” is the same as the average – To calculate the mean: Add up all of the numbers in the data set Divide the answer by the number of numbers that were there Example: Jane wants to improve her economics grade and is hoping to get a B in the course. Her test grades are 70, 84, 84, 86 and 71. What is her average grade for these tests?

3. Mean/Average Example: Jane wants to improve her economics grade and is hoping to get a B in the course. Her test grades are 70, 84, 84, 86 and 71. What is her average grade for these tests? First we add all the numbers in the set of data: 70 + 84 + 84 + 86 + 71 = 395 Then we take that answer and divide by the number of numbers we just added: 395/5 = 79 So, Jane’s average grade for those 5 tests was 79

4. Mean/Average Example: – Tim sold 2 paintings for $200 each, one for $50 and another for $100. What was the average price he got for a painting? – Step one – each painting is a point of data Add 200+200+50+100 = 550 – Step two – divide by the number of data points 550/4 = 137.5 The average price of Tim’s paintings is $137.50

5. Median The median is a number in the middle of a group of numbers. To find a median, follow these steps: – Arrange the numbers in order from smallest to largest. – The number in the middle is the median. When two numbers are in the middle of a group, the median is the mean, or average, of these two numbers. Example: Find the median for the following data set: 2, 8, 4, 11, 6

6. Median Find the median for the following data set: 2, 8, 4, 11, 6 Step one – rearrange 2, 4, 6, 8, 11 Step two – the one in the middle is the median Six is the median of this data set.

7. Median The weekly salaries of six employees at McDonalds are: $140, $220, $90, $180, $140, $200. What is the median salary for these employees?

8. Median The weekly salaries of six employees at McDonalds are: $140, $220, $90, $180, $140, $200. What is the median salary for these employees? Step 1 – rearrange Step 2 – identify middle number(s) – 90, 140, 140, 190, 200, 220 Two numbers are in the middle, so to determine the median, we find the mean or average of those two numbers. 140 and 190 are the middle numbers, so we’ll add them together and then divide by 2 to find the average. – 140 + 190 = 330 – 330/2 = 165 The median salary for these employees is $165/week.

9. Mode Mode: the number in a set of numbers that appears most often. This is the easiest one. Just find the number that occurs most in the data set. If no number occurs more than the others, there is considered to be no mode.

10. Mode The grades for 8 students in Math 40 this quarter are as follows: 3.4, 2.8, 2.9, 3.0, 4.0, 2.6, 3.6, 4.0 What is the mode grade for these students?

11. Mode The grades for 8 students in Math 40 this quarter are as follows: 3.4, 2.8, 2.9, 3.0, 4.0, 2.6, 3.6, 4.0 What is the mode grade for these students? The only number that appears more than once is 4.0; therefore 4.0 is the mode of this set.

12. Mean, Median, and Mode You should now be able to do the work on pages 119 – 121 of your book. Check your answers with the posted answer key when you’re done.