Averages (Mean, Median, Mode, Range)
Mean (average): Sum all values ÷ count. Total = mean × count.
Finding a missing value: If 5 tests average 88, their total = 5 × 88 = 440. Subtract the known scores to find the missing one.
Median: Order all values; the middle value is the median. With an even count, average the two middle values.
Mode: The most frequently occurring value. A set can have multiple modes or none.
Range: Highest − lowest. Measures spread, not center.