"prt sc Test: Mean: SD: # Difference Squared WBC X from X Difference from X 6.5 Range +/- 1SD Range +/- 2SD Range +/- 3SD 2 6 . 6 3 6.7 4 6. 8 Procedure for calculating mean and 15 6. 9 standard deviation: 6 6 . 9 1. Record control data into the first column 7 7.0 2. Find the sum of column one by adding all values together 8 3. Calculate the average, x 9 4. Calculate and record in column two 7 . 1 individual differences from the average 10 7. 4 5. Square each individual difference in column two, and record in column three 1 1 7.5 6. All column three to get the total 12 7. 6 7. Calculate the Standard Deviation using the equation below 13 7. 6 X = each individual measurement 14 7.7 N = total number of measurements 15 7.8 X = mean 16 7.8 Mean = Sum of X 17 8. D N 18 8 . 1 Standard Deviation = 19 8.4 8.5 Sum of Squared Difference from X 20 N- 1 Sum