Lesson Plan - Get It!
Have you ever opened a bag of candy to count how many pieces were inside? Maybe you noticed that your bag did not have the same amount as your friend's bag. Not all packages of candy will have the same amount. If you want to know how many pieces of candy each bag will have, you will need to find the mean, or average.
"Mean" is another word for "average."
The mean is a very useful concept when trying to identify the value of something. Finding the mean is used most often in grading, pricing, sports, and weather. Have you ever heard someone on the TV or radio say, "The average temperature for this time of year is 50 degrees?" That means that during that time of the year, the temperature is usually around 50 degrees.
The mean, or average, is found by following these steps:
- Add up the series of numbers.
- Divide the sum by the number of items in the series.
Another way to think of it is, "the sum divided by the count."
Here is a short song to help you remember how to find the mean:
Sing to the tune of "Row, Row, Row, Your Boat":
Add the numbers, then
Count the numbers and divide.
Let's go through an example so you can see each step:
Find the mean, or average, of 7, 9, 2, 6, 13, 11.
Step 1 Add up the numbers: 7 + 9 + 2 + 6 + 13 + 11 = 48.
Step 2 Next, divide the sum, 48, by the number of numbers. If you count the numbers, you see there are 6 numbers. Divide 48 by 6 and get 8. The mean, or average, is 8.
Sometimes, the mean won't be a whole number. If you and a friend each have a bag of candy, how could you find the mean amount of candies in a bag?
Let's say that your bag has 13 candies. Your friend's bag has 14 candies. How many candies are in bag, on average?
Step 1 Add up the numbers: 13 + 14 = 27.
Step 2 Next, divide the sum, 27, by the number of numbers. If you count the numbers, you see there are 2 numbers. Divide 27 by 2. If you do long division, you should get 13 with a remainder of 1. The mean, or average, number of candies in a bag is about 13.5 or 13½. This means that there will be about 13½ candies per bag, but it could be more or less than that amount.
Discuss with a teacher or parent:
- Explain how to find the average of a set of numbers.
- Can the answer be an amount that is not a whole number?
- Describe a time when finding the mean would be helpful.
Now that you know how to find the mean, go to the Got It? section to practice finding the mean by playing the "Finding the Mean" game!