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## Mean

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**Mode**Mean Range Median WHAT DO THEY ALL MEAN?**All of the previous words can be summed up with the phrase**MEASURES OF CENTRAL TENDENCY**Mean**This is what we usually mean when we say “What’s my average.” We could say, “What grade do I normally get?”**How is the mean of a set of numbers found?**• Add all the numbers in the set together. • Divide the sum by the number of data items in the set. • The quotient is the mean of the set of numbers. • Example: 10, 18, 12 and 16 • Add 10 + 18 + 12 + 16 = 56 • Divide 56 by 4 • The mean is 14**Median**• Is the number that is in the middle of a set of numbers. • Half the numbers are below the median and half the numbers are above the median**How is the median of a set of numbers found?**• Arrange the numbers in the set in order from least to greatest. • Count in from the ends. • The middle number is the median of a set of numbers. • If more than one number is in the middle of the set of numbers, the mean of those two numbers is the median of the set of numbers.**Your grades on five tests:**95, 87, 92, 100, and 85 Put them in order from least to greatest 85, 87, 92, 95, 100 Your median test grade is 92 – half the time you score below 92 and half the time below 92 The middle number is the median**Your grades on six tests:**95, 87, 92, 100, and 94 Put them in order from least to greatest 85, 87, 92, 94, 95, 100 The median is the mean of 92 and 94 Or 92 + 94 = 186 186 divided by 2 = 93 The middle is between 2 numbers**How do I identify the mode of a set of numbers?**• Arrange the set of numbers in order from least to greatest. • The number that occurs the most often is the mode of that set of numbers.**Mode**The number in a data set that occurs most often Your grades: 95, 87, 85, 100, 100 Your mode is 100 Most of the time you get a 100**You don’t have to have a mode…….**Some data sets have no mode or no number that occurs more than others Some might have two modes**RANGE**Asks the Question: How spread out is my data? Another way to describe data**How is the range of a set of numbers identified?**• Arrange the numbers in the set in order from least to greatest. • Subtract the lowest number from the highest number in the set of numbers. • The difference of the two numbers is the range of a set of numbers.**Back to your test Scores:**95, 87, 92, 100, and 94 Your highest score is a 100 Your lowest score is 87 Your range is 100 – 87 = 13 The range = 13**It’s Time To Practice!**Number of pets owned by 7 students: 2, 1, 1, 4, 3, 2, 1 2 What is the mean What is the median 2 1 What is the Mode 3 What is the Range**4 ways to describe data**The Mean – what we usually think of as the average….. The Median – The middle number in a data set…..50% of the numbers are above and 50% are below the median The Mode – The number that occurs most often….. The Range – the difference between the smallest and bigest number…..