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MEAN. LET’S CHECK WHAT YOU KNOW. Simplify 3+2+45+67+78+96 = (45+67+56+43+23)= 3 3. 9.261 = 3 4. 255 ÷ 4 = 5. 137 ÷ 5 =. MEAN. The MEAN of a set of data is the sum of the data divided by the number of items. Mean = sum of data number of items.
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MEAN CONFIDENTIAL
LET’S CHECK WHAT YOU KNOW • Simplify • 3+2+45+67+78+96 = • (45+67+56+43+23)= 3 3. 9.261 = 3 4. 255 ÷ 4 = 5. 137 ÷ 5 = CONFIDENTIAL
MEAN • The MEAN of a set of data is the sum of the data divided by the number of items. • Mean = sum of data number of items CONFIDENTIAL
Example-1 • Find the mean of the following observations: 41, 80, 112, 86, 21 • Mean = (41+80+112+86+21) 5 = 340 = 68 5 CONFIDENTIAL
Example-2 • Find the mean of the following data: 3, 10, 12, 7, 9, 8, 7. • Mean = Sum of data Number of data = 3+10+12+7+9+8+7 7 = 56 = 8 7 CONFIDENTIAL
Mean • A number that helps describe all of the data in a data set is an average or a measure of central tendency. • One of the most common measures of central tendency is the mean. CONFIDENTIAL
Outliers • In statistics, a set of data may contain a value much higher or lower than the other values. • This value is called an outlier. • Outliers can significantly affect the mean. CONFIDENTIAL
Example of Outliers • Identify the outlier in the temperature data. Then find the mean with and without the outlier. Describe how the outlier affects the mean of the data. CONFIDENTIAL
Compared to the other values, 40°F is extremely low. So, it is an outlier. Mean with outlier = 80+81+40+77+82 5 = 360 5 =72 Mean without outlier = 80+81+77+82 4 = 320 4 =80 Example of Outliers With the outlier, the mean is less than all but one of the data values. Without the outlier, the mean better represents the values in the data set CONFIDENTIAL
Your Turn! • Find the mean for the snowfall data with and without the outlier. Then tell how the outlier affects the mean of the data. CONFIDENTIAL
BREAK CONFIDENTIAL
Have Fun! http://www.thekidzpage.com/freekidsgames/games/breakdown/index.html CONFIDENTIAL
Do it by yourself • The marks obtained by 10 students in a test are: 90, 75, 80, 65, 78, 65, 80, 77, 86 and 74. Find the mean. CONFIDENTIAL
Practice Problems Find the mean of the following: • 72,55,48,61,63,37 • 75,82,81,95,92 • 7,15,9,12,10,13 • 365,225,118,132,240 • 15,24,14,48,27,20 CONFIDENTIAL
More problems • The marks Christy got in 6 tests are : 65 72, 59, 81, 68, 72. while another student Fredy wrote only 5 of these tests and his marks are 71, 54, 68, 82, 75. Whose overall performance is better? CONFIDENTIAL
Assignments • The minimum temperatures in Celsius recorded on various days of a week are 220, 250, 230, 210, 200, 270. Find their arithmetic mean. • Calculate the mean weight of the students from the following data: 135, 184, 94, 288, 49, 200 CONFIDENTIAL
Assignment 3. The maximum daily temperature (in C0) for the first week of a month in Melbourne are 37, 35, 38, 34, 39, 36 and 33. calculate the mean temperature for the week. Find the mean of : 4. 3, 7, 8, 5, 6, 9, 6, 4, 6 5. 25, 31, 27, 29, 32, 25, 28, 25. • 3, 5, 1, 5, 7, 3, 2, 3 • 2, 3, 4, 4, 1, 6, 4, 3. CONFIDENTIAL
Assignment 8. Which piece of data in the data set 98, 103, 96, 147, 100, 85, 546, 120, 98 is an outlier? 9. Write a set of data in which the mean is affected by the outlier. CONFIDENTIAL
Let’s Review what we studied today • Mean of a set of data is the sum of the data divided by the number of items. • Mean = sum of data number of items CONFIDENTIAL
Thanks! CONFIDENTIAL