MathDB
Harmonica

Source: 2018 AMC 8 #10

November 20, 2018
2018 AMC 8AMC 8

Problem Statement

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?
<spanclass=′latex−bold′>(A)</span>37<spanclass=′latex−bold′>(B)</span>712<spanclass=′latex−bold′>(C)</span>127<spanclass=′latex−bold′>(D)</span>74<spanclass=′latex−bold′>(E)</span>73<span class='latex-bold'>(A) </span>\frac{3}{7}\qquad<span class='latex-bold'>(B) </span>\frac{7}{12}\qquad<span class='latex-bold'>(C) </span>\frac{12}{7}\qquad<span class='latex-bold'>(D) </span>\frac{7}{4}\qquad <span class='latex-bold'>(E) </span>\frac{7}{3}
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