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, select Percentage (%) in the Numbers 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%.