Standard Deviation Example Sums. With samples we use n 1 in the formula because using n would give us a biased estimate that consistently underestimates variability. Example question 1.
S 2 92 2 3 42. Sample standard deviation s sqrt frac sum x bar x 2 n 1 13 5 6 1 2 7 1 643. Sum 6 25 20 25 2 25 6 25 30 25 0 25 65 5.
S 31 6 9 6 2 2.
Add up all the numbers and divide by the total number of data points. The sample standard deviation would tend to be lower than the real standard deviation of the population. A survey conducted by an automobile company showed the number of cars per household and the corresponding probabilities. Upon grading the exam it was found that the mean score was 95 with a standard deviation of 12.
