2020 · Q45
For two observations, the sum is S and product is P. What is the harmonic mean of these two observations?
Elementary MathematicsStatistics
- A2S/P
- BS/2P
- C2P/S
- DP/2S
Explanation
The harmonic mean of a and b is 2/(1/a + 1/b) = 2ab/(a + b). With P = ab and S = a + b, this is 2P/S. For instance, the harmonic mean of 2 and 3 is 2·6/5 = 12/5.