Chapter 5 – 9 Measure of Central Tendency UNIT 2 Chapter 5 – 9 Measure of Central Tendency

Vocabulary When you have a list of numerical data, it is often helpful to use one or more numbers to represent the whole set. These numbers are called measures of central tendency. There are 3 types of measures of central tendency: Mean (also known as average): the sum of the data divided by the number of items in the data set Median: the middle number of the data set when numbers are written smallest to biggest OR the mean of the middle two numbers Mode: the number or numbers that occur most often

Finding Mean, Median, and Mode Find the mean, median, and mode. The shoe size of several students are listed below: 4, 6, 12, 5, 8 Mean: 𝑠𝑢𝑚 𝑜𝑓 𝑠𝑖𝑧𝑒𝑠 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑠𝑡𝑢𝑑𝑒𝑛𝑡𝑠 = 4+6+12+5+8 5 = 35 5 = 7 Median: 4, 5, 6, 8, 12 = 6 Mode : There is no mode since there isn’t a number that occurs more than once

Which measure of central tendency do I use? Use mean – when the data set of number are relatively close to each other. There isn’t one number that is larger or smaller than the rest Use median – when the data set is skewed. In other words, use median if there is a data value that is much larger or much smaller than the rest Use mode – when you are trying to find which data set occurs the most. Mode is the used the least.

Let’s Try Some Examples! Find the mean, median, and mode. If needed, round the nearest tenth. 2, 8, 5, 18, 3, 5, 6 11, 12, 12, 14, 16, 11, 15 56, 77, 60, 60, 72, 100

Let’s Check Our Answers! Find the mean, median, and mode. If needed, round the nearest tenth. 1) 2, 8, 5, 18, 3, 5, 6 Mean: 47 ÷ 7 = 6.7 Median: 2, 3, 5, 5, 6, 8, 18 Mode: 5 2) 11, 12, 12, 14, 16, 11, 15 Mean: 91 ÷ 7 = 13 Median: 11, 11, 12, 12, 14, 15, 16 Mode: 11 and 12 3) 56, 77, 60, 60, 72, 100 Mean: 425 ÷ 6 = 70.8 Median: 56, 60, 60, 72, 77, 100 Mode: 60 60+72=132÷2 =66