The geometric mean is a variation on the standard arithmetic mean (where the numbers are totalled, then divided by the amount totalled). The latter of these two can be generalised as:
\(\frac{a_{1} + a_{2} + a_{3} ... + a_{n}}{n}\)
The difference with a geometric mean is that instead of totalling the numbers, the product is found; similarly instead of a division stage at the end, an appropriate root is found:
\(sqrt[n]({a_{1}a_{2}a_{3}...a_{n}})\)
Therefore for this question n = 2, since there are two numbers. Substituting in:
\(sqrt{7 * 11}\) = \(\sqrt{77}\) = 8.77496438739 ≈ 8.8 (2sf)
