Averages and Range

Using the frequencies

• A frequency table lists each value alongside how many times it occurs, so the frequencies must be used as counts
• Read the mode as the value against the biggest frequency, not that frequency figure itself
• The mean needs the total of all the data, found by multiplying each value by its frequency and adding
  • Mean = Σ(frequency × value) ÷ total frequency
• The median is found by counting through the frequencies until the middle position is reached
  • With n values the median sits at position (n + 1) ÷ 2
• Adding an extra column for frequency × value keeps the working visible and is what the method marks reward