Harmonic mean of $$$9$$$, $$$24$$$

Find the harmonic mean of $$$9$$$, $$$24$$$.

The harmonic mean of data is given by the formula $$$H = \frac{n}{\sum_{i=1}^{n} \frac{1}{x_{i}}}$$$, where $$$n$$$ is the number of values and $$$x_i, i=\overline{1..n}$$$ are the values themselves.

Since we have $$$2$$$ points, $$$n = 2$$$.

The sum of the reciprocals of the values is $$$\frac{1}{9} + \frac{1}{24} = \frac{11}{72}$$$.

Therefore, the harmonic mean is $$$H = \frac{2}{\frac{11}{72}} = \frac{144}{11}$$$.

The harmonic mean is $$$\frac{144}{11}\approx 13.090909090909091$$$A.