Warm Up A: Make a bar graph of this data B: Why is it inappropriate to make a circle graph of this data?
Properties of the Mean The Mean of 2, 3, and “N” numbers
FINDING THE MEAN (2 numbers) To find the mean of two numbers, you add them and divide them by 2. So if the numbers are “a” and “b” and the mean is “m” then:
example In January in Dulut, Minnesota, a typical high temperature is 18 degrees Fahrenheit and a typical low temperature is -1 degrees Fahrenheit. The mean of these numbers is: Notice that 2 • 8.5 = 17 (the sum of the two temperatures)
Finding the mean (3 numbers) To find the mean of 3 numbers, you add them and divide the sum by 3. If the numbers are “a” “b” and “c” then:
Practice Problem Mykia has scored 86, 83, 91, and 75 on her first four tests in a class. What score does she need on the fifth test to average 85 for all five tests?
Geometrically proving the mean Here are the scores of 10 students on a quiz: 100, 100, 100, 100, 90, 60, 60, 60, 50, 50 The sum of the scores is 770, so the mean is 77.
Balance property If “m” is the mean of a set of numbers. Then the sum of the distances to “m” from the numbers greater than “m” in the set equals the sum of the distances to “m” from the numbers less than “m” in the set. How you may ask??
Practice Makes Perfect Ishi has a mean score 57 on the first 5 of 6 tests she must take this semester. She wants to know what she has to score on the last test to average 60 for all 6 tests A: Answer Ishi’s question by solving an equation B: Answer Ishi’s question by calculating distances from the mean.