Mean, Median, Mode, Range & Stem and Leaf Plots Measures of Central Tendency

Mean The mean is the Average of a group of numbers It is helpful to know the mean because then you can see which numbers are above and below the mean

Mean Example Here is an example test scores for Ms. Math’s class To find the Mean, first you must add up all of the numbers = 440 Now, since there are 5 test scores, we will next divide the sum by ÷5 = 88 The Mean is 88!

Another Mean Example Here is an example test scores for your math class x – test you haven’t taken yet What if you wanted to get at an 85 in your math class for your final grade. What is the lowest you can make on the test you haven’t taken yet? How would you figure it out? Let’s see if we write and solve this out. X = 77

Median The Median is the middle value on the list. The first step is always to put the numbers in order from least to greatest.

Median Example First, let’s examine these five test scores We need to put them in order The number in the middle is In this case, the Median is 86!

Median Example #2 Now, let’s try it with an even number of test scores First, we will put them in order This time, there are two numbers in the middle, 86 and Now we will need to find the Average of these two numbers, by adding them and dividing by two = ÷2= 87 Here the Median is 87

Mode The Mode refers to the number that occurs the most frequently. It’s easy to remember… the first two numbers are the same! MOde and MOst Frequently!

Mode Example Here is an list of temperatures for one week. Mon. Tues. Wed. Thurs. Fri. Sat. Sun. 77° 79° 83° 77° 83° 77° 82° Again, We will put them in order. 77° 77° 77° 79° 82° 83° 83° 77° is the most frequent number, so the mode= 77°

Range The range is the difference between the highest and the lowest numbers of the series. All we have to do is find the highest number and the lowest number and subtract!

Range Example Let’s look at the temperatures again. 77° 77° 77° 79° 82° 83° 83° The highest number is 83, and the lowest is 77. All you need to do is subtract! 83-77= 6 In this case, the Range is 6

Stem and Leaf Plots This a way to display data in an organized manner What numbers does this stem and leaf plot represent?

Stem and Leaf Plots Can you find the mean, median, mode, and range of the stem and leaf plot? Stem and Leaf Plot Numbers: 2, 4, 5, 13, 16, 17, 18, 18, 20, 22, 23, 27, 29

Now YOU try it!!! This is the AVERAGE Family! Dad MomJackAlex Katie

The Average Family Make a stem and leaf plot of the family’s ages. Dad MomJackAlex Katie

Mean Here are the ages again… Dad- 34, Mom- 33, Jack- 5, Alex- 4, Katie- 1 What is the Mean? Remember… Mean is the AVERAGE

Mean Remember, to find the mean, we have to first add up all of the numbers = 77 Then, since there are 5 people in the family, we next divide by 5. 77÷5= 15.4 The Mean in this case is 15.4

Median Here are the ages again… Dad- 34, Mom- 33, Jack- 5, Alex- 4, Katie- 1 What is the Median? Remember… Median is the MIDDLE NUMBER

Median Remember, to find the mean, we have to first put all of the numbers in order The Mean in this case is 5

Mode Here are the ages again… Dad- 34, Mom- 33, Jack- 5, Alex- 4, Katie- 1 What is the Mode? Remember… Mode is the MOST FREQUENT

Mode Remember, to find the mode, we have to first put all of the numbers in order The Mode, in this case, does not exist. Since there is not a number that appears most often, you write no mode.

Range Here are the ages again… Dad- 34, Mom- 33, Jack- 5, Alex- 4, Katie- 1 What is the Range? Remember… Range is the DIFFERENCE

Range Remember, to find the range, we have to first put all of the numbers in order The highest age is 34, and the lowest is 1 Now we need to subtract to find the difference 34-1= 33 The range is 33

Now let’s see how you do on yesterday and today’s concepts… Pg. 62 & , evens only AND Pg , 8, 20-22, 25 all problems