Calculate the Average: Finding Mean of 20 and 10

Q: Why do I divide by 2 when finding the average of two numbers?

Because the average represents the middle value between your numbers. Dividing by 2 splits the total sum equally, giving you the point halfway between 10 and 20.

Q: What if I have more than two numbers?

The same rule applies! Add all the numbers together, then divide by how many numbers you added. For 3 numbers, divide by 3; for 5 numbers, divide by 5.

Q: How can I check if my average is reasonable?

Your average should always be between the smallest and largest numbers you're averaging. If it's outside this range, double-check your calculation!

Mean Calculation with Two Values

Calculate the average of $20$ and $10$ .

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations

00:00 Calculate the average

00:03 To calculate the average, we need to divide the sum by the number of occurrences

00:08 Let's sum up the numbers

00:15 And divide by the number of occurrences (2)

00:20 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Calculate the average of $20$ and $10$ .

Step-by-step solution

To calculate the average of the numbers 20 and 10, we will follow these steps:

Step 1: Add the two numbers together. We have $20 + 10 = 30$ .
Step 2: Divide the sum by the number of values, which is 2. So, we have $\frac{30}{2} = 15$ .

Therefore, the average of 20 and 10 is $15$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Definition: Average equals sum of values divided by count
Formula: For 20 and 10: $\frac{20 + 10}{2} = \frac{30}{2} = 15$
Check: Both values should be reasonably close to the average result ✓

Common Mistakes

Avoid these frequent errors

Forgetting to divide by the number of values
Don't just add the numbers and stop = 30 instead of 15! This gives you the sum, not the average. Always divide the sum by how many numbers you added together.

Practice Quiz

Test your knowledge with interactive questions

Calculate the average of $$ 10 $$ and $$ 12 $$ .

FAQ

Everything you need to know about this question

Why do I divide by 2 when finding the average of two numbers?

Because the average represents the middle value between your numbers. Dividing by 2 splits the total sum equally, giving you the point halfway between 10 and 20.

What if I have more than two numbers?

The same rule applies! Add all the numbers together, then divide by how many numbers you added. For 3 numbers, divide by 3; for 5 numbers, divide by 5.

Can the average be a decimal?

Absolutely! If your sum doesn't divide evenly, you'll get a decimal answer. For example, the average of 10 and 11 is $\frac{21}{2} = 10.5$ .

How can I check if my average is reasonable?

Your average should always be between the smallest and largest numbers you're averaging. If it's outside this range, double-check your calculation!

Is there a faster way to find the average of two numbers?

Yes! For just two numbers, you can think of it as finding the midpoint. The average of 10 and 20 is halfway between them: $10 + \frac{20-10}{2} = 15$ .

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