Using the Normal Probability Calculator applet

After specifying an axis label (identify the variable for the distribution), and the mean and standard deviation of the distribution (where you may need to calculate the standard deviation first), press the Scale to Fit button.

Then check the box next to the < sign.  Enter the observation value (our ) in the X box and press Enter. Once you press Enter, the Z box and the “prob” (probability) box will update. 

If you want the probability above a value, change the < sign to >.

If you want the probability between two values or outside two values, activate and use both rows.

You can also enter a Z value or a probability and have the applet determine the other two values.

You can also move the blue line(s) and the applet will update the X, Z, and probability values automatically.