2017AP Statistics Summer Packet.pdf

The variance 2 s of a set of observations in the

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The variance 2 s of a set of observations in the standard deviation squared, meaning the average of the squares of the deviation of the observations from their mean.
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13 Example: Below is a list of test scores earned by AP Statistics students on the chapter 1 test. Find the mean and standard deviation. 88 72 96 68 81 1. Find the sample mean: 8 8 7 2 9 6 6 8 8 1 8 1 5 x 2. i x i x x 2 i x x 88 88 81 = 7 (7) 2 = 49 72 72 81 = -9 (-9) 2 = 81 96 96 81 = 15 (15) 2 = 225 68 68 81 = -13 (-13) 2 = 169 81 81 81 = 0 (0) 2 = 0 1. 2 i x x = 49 + 81 + 225 + 169 + 0 = 524 2. 2 5 2 4 5 2 4 1 3 1 1 5 1 4 i x x n . This is the variance! 3. 2 131 11.45 1 i x x n . This is the standard deviation.
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14 Example Problem: TI 83/84 Calculator Instructions: Your calculator will compute the mean, standard deviation, and five number summary for you. 1. Press the STAT button on your calculator. #1 will be highlighted. Press ENTER. 2. Enter the data into L 1 . 3. Press 2 nd MODE (Quit) to exit the screen. 4. Press STAT, then move the cursor to the right so CALC is highlighted. #1 should be selected. Press ENTER. 5. The screen of your calculator will say 1-Var Stats. Type in L 1 (since your data is in List 1) ENTER. 6. The sample mean, x , is the first value given. Sx is the sample standard deviation. Scroll down to find the five number summary. Now, complete Worksheet C (Center, Spread, and 5-Number Summary); page 31
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