This application calculates and shows probability for a standard normal curve. You set the z values for A and B and the probability for an event having a z-score less than B and greater than A is given by the blue area between A and B. The z-scores A and B may be set by entering a numbers in the boxes or dragging A or B (on the x-axis) back and forth with the mouse.

Alternatively you could adjust A and/or B for a certain probability (area under the curve) and determine the z-scores which give that probability. [b]Note[/b]: The values given here may not agree exactly with a standard normal table. If you use them in calculations for homework or test questions, they may not be [i]exactly [/i]the answers expected. Use this to help you get the idea of what is happening and get approximate values which will help you know if you are on the right track using the table.