MASTERING THE MEAN
From the basics to word problems. Read the lesson carefully, then take the 5-item quiz at the bottom!
The MEAN (also called the average) is the simplest way to find the typical value of a group of numbers. Think of it as distributing all the values equally among the group.
ADD THEM ALL
Find the sum of every number in the set
DIVIDE BY COUNT
Divide the total sum by how many numbers there are
Numbers: 3, 5, 7
Step 1 (Add): 3 + 5 + 7 = 15
Step 2 (Divide): 15 ÷ 3 = 5
So the MEAN is 5!
Let's try with 5 numbers. The process is exactly the same. Don't let the bigger numbers intimidate you!
Numbers: 10, 20, 30, 40, 50
Step 1: 10 + 20 + 30 + 40 + 50 = 150
Step 2: 150 ÷ 5 (numbers) = 30
The mean is 30.
Scenario: Anna took 5 math quizzes. Her scores were 85, 90, 88, 92, and 95. What is her mean (average) score?
1. Add all scores: 85 + 90 + 88 + 92 + 95 = 450
2. Divide by the number of quizzes (5): 450 ÷ 5 = 90
Anna's mean score is 90.
Scenario: The mean of 4 numbers is 10. If three of the numbers are 8, 9, and 12, what is the fourth number?
1. If the mean of 4 numbers is 10, their total sum must be: 10 × 4 = 40.
2. Add the 3 known numbers: 8 + 9 + 12 = 29.
3. Subtract the sum of the 3 numbers from the total sum: 40 - 29 = 11.
The fourth number is 11.
Quiz Time!
Read each question carefully. You need to answer all questions before submitting. Good luck!
Mathemalupit | Interactive Math Review & Quiz