Harmonic mean of $$$7$$$, $$$21$$$

The calculator will find the harmonic mean of $$$7$$$, $$$21$$$, with steps shown.

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Find the harmonic mean of $$$7$$$, $$$21$$$.

Solution

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 $$$\frac{1}{7} + \frac{1}{21} = \frac{4}{21}$$$.

Therefore, the harmonic mean is $$$H = \frac{2}{\frac{4}{21}} = \frac{21}{2}$$$.

Answer

The harmonic mean is $$$\frac{21}{2} = 10.5$$$A.