Calculate the Arithmetic Mean: Finding Average of 1 and 12

To solve this problem, we need to calculate the average of the numbers 1 and 12. The average can be calculated using the formula:
$\text{average} = \frac{\text{sum of numbers}}{\text{number of values}}$.

Now, let's work through the steps:
Step 1: Calculate the sum of the numbers:
$1 + 12 = 13$.

Step 2: Determine the number of values, which is 2 in this case.
Step 3: Apply the average formula:
$\text{average} = \frac{13}{2} = 6.5$.

Therefore, the average of the numbers 1 and 12 is $6.5$.

Considering the given answer choices, choice 1 with $6.5$ is the correct answer as per our calculations.