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jmc

prealgebra junior

Problem

The harmonic mean of a set of non-zero numbers is the reciprocal of the average of the reciprocals of the numbers. What is the harmonic mean of 1, 2, and 4?
(A)
(B)
(C)
(D)
Solution
The sum of the reciprocals is . Their average is . Taking the reciprocal of this gives .
Final answer
C