Discussion

The geometric mean of 4, 8 and 16 is

Answer: B

The geometric mean of 4, 8 and 16 is 8.0. It is the cube root of the product of the three numbers.

\[ GM = (4 \times 8 \times 16)^{1/3} \]

\[ = (512)^{1/3} = 8 \]

The arithmetic mean would be 9.33, which is option A and a common slip. The values 4.8 and 10.2 do not come from either mean. The answer is option B.

A useful check is that the three numbers form a geometric progression with ratio 2, and the middle term of such a progression is its geometric mean.

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