2025 · Q95
A distribution has 3 components with frequencies 45, 40, 55 and means 2, 2.5, 2. What is the combined mean?
Elementary MathematicsStatistics
- A2.14
- B2.5
- C2.0
- D3.14
Explanation
Combined mean = (45*2 + 40*2.5 + 55*2)/140 = 300/140, about 2.14. The component means must be weighted by their frequencies. A simple average of 2, 2.5 and 2 would ignore the different group sizes.