Calculate the mean of the following numbers: 12, 15, 22, 9, 18.

To find the mean of a set of numbers, you need to sum all the numbers and then divide that total by the quantity of the numbers.

First, add the numbers together:

12 + 15 + 22 + 9 + 18 = 76

Next, count how many numbers there are in the set. In this case, there are five numbers.

Now, divide the total sum by the count:

76 ÷ 5 = 15.2

Thus, the mean of the numbers 12, 15, 22, 9, and 18 is 15.2. This calculation clearly shows how the mean is derived as the average of the numbers provided in the question, confirming that the answer is accurate and well-supported by mathematical principles.