11.4 Calculating Probability or Cumulative Area
We can use the NORM.DIST(x,mean,standard_dev,TRUE)
function to calculate the probability that variable x falls below or at a specified value. Recall that a percentile in a normal distribution also corresponds to the area to the left (cumulative area) of a specific value.
- Select cell L1 and enter the label Percentile.
- Go to cell L2 and enter the formula
= NORM.DIST(J2,$H$2,$H$4,TRUE)
.
Note: Remember to include the $
symbol.
- Select cell L2 and place the mouse pointer in the lower right corner of the selected cell until it becomes a
+
sign, and click-drag downward across the range that covers all the values in column K. - In the
Home
tab, selectPercentage
(%) in theNumbers
ribbon to convert the values in Column L to percentages. - Adjust the probability (or percentiles) values to two (2) decimal places.
The data’s percentiles should range from 0.02% to 99.91%.