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Course: Mathematics — Second Preparatory
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Mathematics — Second Preparatory

Text lesson

Measures of Central Tendency

Mathematics — Second Preparatory

Measures of Central Tendency

Worked examples

Worked examples

Comparison aspectMain ideaKeywords
Example 1
  • Find the mean
  • the median and the mode of the values 4
Findmeanmedianmode
Solution
  • The sum of the values is 37
  • and there are 5 values
  • so the mean = 37 ÷ 5 = 7.4. Arranged in order: 4
  • so the median is the middle value 7. The mode is 7
  • because it occurs most often
valuesmeanArrangedorder
Example 2Find the median of the values 3Findmedianvalues
Solution
  • There are 6 values
  • an even number
  • so the two middle values are 8 and 10. The median = (8 + 10) ÷ 2 = 9. The mean = (3 + 5 + 8 + 10 + 12 + 15) ÷ 6 = 53 ÷ 6 ≈ 8.83
valuesevennumbermiddle
Example 3
  • In a frequency table
  • the value 2 has frequency 3
  • the value 5 has frequency 4
  • the value 8 has frequency 2
  • and the value 10 has frequency 1. Find the mean and the median
frequencytablevalueFind
Comparison aspectMain ideaKeywords
Solution
  • The sum of the frequencies = 3 + 4 + 2 + 1 = 10. The sum of (value × frequency) = 6 + 20 + 16 + 10 = 52. So the mean = 52 ÷ 10 = 5.2. For the median
  • arrange the 10 values: 2
  • 10. The 5th and 6th values are both 5
  • so the median = 5
frequenciesvaluefrequencymean
Example 4
  • The mean of four numbers is 6
  • and three of them are 5
  • 7 and 8. Find the fourth number
meanfournumbersthree
SolutionThe sum of the four numbers = 6 × 4 = 24. The sum of the three known numbers = 5 + 7 + 8 = 20. So the fourth number = 24 − 20 = 4fournumbersthreeknown
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