Determine the variation in this unordered data set by finding the range.12, 13, 18, 21, 17, 12, 12, 21, 18

1. Break Down the Problem

To find the range of a data set, we need to determine the maximum and minimum values in the set and then calculate the difference between them.

2. Relevant Concepts

The formula for finding the range is as follows: $\text{Range} = \text{Maximum} - \text{Minimum}$ Where the maximum is the largest value in the data set and the minimum is the smallest value.

3. Analysis and Detail

Let's identify the maximum and minimum values in the given data set:

• Data Set: $12, 13, 18, 21, 17, 12, 12, 21, 18$
• Maximum Value: 21
• Minimum Value: 12

Now, apply the formula: $\text{Range} = 21 - 12$

4. Verify and Summarize

Calculating this gives: $\text{Range} = 9$ Thus, we can confirm that the calculations are correct.

Final Answer

The range of the data set is $9$.