Given 10 sample values 9,25,22,14,11,15, 21,19,13,23 _ Sample mean = x = Sample mode = sample median = sample range = sample standard deviation = Arrange them in order, smallest to largest, 9, 11. 13, 14, 15, 19, 21, 22, 23, 25 No number appears most, so there is no sample mode. To find the sample median: There is an even number of numbers, so we take the two middle ones 15 and 19, and average them= 17 Median = 17 Sample range: Subtract the smallest value 9 from the largest value 25 Range = 25 - 9 = 16 Now we make this array, then total the column of x-values, then divide by 10, the number of numbers. That number is _ x , the sample mean. _ _ x | x-x | (x-x)² ------------------- 9 | | 11 | | 13 | | 14 | | 15 | | 19 | | 21 | | 22 | | 23 | | 25 | | ------ ------ 10)172 ) _ ---- ------- x = 17.2 _ Fill in the column with heading x - x by subtracting 17.2 from each member of the first column: _ _ x | x-x | (x-x)² ------------------- 9 |-8.2 | 11 |-6.2 | 13 |-4.2 | 14 |-3.2 | 15 |-2.2 | 19 | 1.8 | 21 | 3.8 | 22 | 4.8 | 23 | 5.8 | 25 | 7.9 | ------ ------ 10)172 ) _ ---- ------- x = 17.2 Don't bother adding that column for you will always get 0. _ Square every member in the x-x column and add them up: _ _ x | x-x | (x-x)² ------------------- 9 |-8.2 | 67.24 11 |-6.2 | 38.44 13 |-4.2 | 17.64 14 |-3.2 | 10.24 15 |-2.2 | 4.84 19 | 1.8 | 3.24 21 | 3.8 | 14.44 22 | 4.8 | 23.04 23 | 5.8 | 33.64 25 | 7.9 | 60.84 ------ ------ 10)172 )273.60 _ ---- ------- x = 17.2 Then divide that by 1 less than the number of numbers. Since there are 10 numbers, you will divide by 9. That is the variance, s². _ _ x | x-x | (x-x)² ------------------- 9 |-8.2 | 67.24 11 |-6.2 | 38.44 13 |-4.2 | 17.64 14 |-3.2 | 10.24 15 |-2.2 | 4.84 19 | 1.8 | 3.24 21 | 3.8 | 14.44 22 | 4.8 | 23.04 23 | 5.8 | 33.64 25 | 7.9 | 60.84 ------ ------ 10)172 9)273.60 _ ---- ------- x = 17.2 s² = 30.40 Now take the square root of the variance s², and that is the sample standard deviation, s: _ _ x | x-x | (x-x)² ------------------- 9 |-8.2 | 67.24 11 |-6.2 | 38.44 13 |-4.2 | 17.64 14 |-3.2 | 10.24 15 |-2.2 | 4.84 19 | 1.8 | 3.24 21 | 3.8 | 14.44 22 | 4.8 | 23.04 23 | 5.8 | 33.64 25 | 7.9 | 60.84 ------ ------ 10)172 9)273.60 _ ---- ------- x = 17.2 s² = 30.40 s = = 5.513619501 Edwin