\( = \overline { X } = \frac { \sum X } { n } = \frac { 81 + 75 + 66 + 16 + 90 + 90 } { 6 } = 69.67 \)

Did you know that the concept of the average, or mean, dates back to ancient civilizations? The Babylonians and Greeks used early forms of averaging to track agricultural yields and property values. It’s fascinating how this simple calculation has stood the test of time and remains a fundamental concept in mathematics and statistics today! Now, when calculating averages, a common mistake is to forget to divide by the correct number of values. In your case, you added up six numbers, so dividing by six was spot on! However, in larger datasets, it's easy to miscount, which can really skew your results. Always double-check your totals and your divisor for accurate averaging!