2020 · Q98
The mean of five observations x, x + 2, x + 4, x + 6, x + 8 is m. What is the mean of the first three observations?
Elementary MathematicsStatistics
- Am
- Bm − 1
- Cm − 2
- Dm − 3
Explanation
The mean of the five observations is x+4 = m; the mean of the first three is x+2 = m-2. Hence option (C). In general the mean of the first three of five equally spaced values is m-2.