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 and
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The reciprocals of and are , and and their average is = . So the harmonic mean of , , and is the reciprocal of which is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions