Find the standard deviation. Round to one more place than the data.
68, 34, 86, 46, 48, 39, 79, 85, 81
pls guys help
Here is a page that uses a simple example to show how to do this.
Simply follow the steps using your numbers.
http://hubpages.com/hub/stddev
Most consists of tedious arithmetic.
To find the standard deviation, follow these steps:
1. Calculate the mean (average) of the data set. Add up all the numbers and divide the sum by the total count of numbers.
(68 + 34 + 86 + 46 + 48 + 39 + 79 + 85 + 81) / 9 = 566 / 9 = 62.89 (rounded to two decimal places)
2. Subtract the mean from each number in the data set.
(68 - 62.89) = 5.11
(34 - 62.89) = -28.89
(86 - 62.89) = 23.11
(46 - 62.89) = -16.89
(48 - 62.89) = -14.89
(39 - 62.89) = -23.89
(79 - 62.89) = 16.11
(85 - 62.89) = 22.11
(81 - 62.89) = 18.11
3. Square each of the differences calculated in step 2.
(5.11)^2 = 26.12
(-28.89)^2 = 835.29
(23.11)^2 = 534.21
(-16.89)^2 = 284.92
(-14.89)^2 = 221.77
(-23.89)^2 = 570.72
(16.11)^2 = 259.92
(22.11)^2 = 488.92
(18.11)^2 = 327.72
4. Find the average of the squared differences. Add up all the squared differences from step 3 and divide by the total count of numbers.
(26.12 + 835.29 + 534.21 + 284.92 + 221.77 + 570.72 + 259.92 + 488.92 + 327.72) / 9 = 3569.49 / 9 = 396.61 (rounded to two decimal places)
5. Take the square root of the average obtained in step 4.
√(396.61) = 19.91 (rounded to two decimal places)
Therefore, the standard deviation of the given data set is approximately 19.91 (rounded to one more decimal place than the data).