Finding a normal probability
The probability that a normally distributed variable, Y, has a value within any range equals the area under the normal curve above this range of values.
To get an approximate answer to the questions below, drag the vertical red lines on the diagram until the diagram shows the required area.
For a more accurate answer, type the end-points of the interval into the text-edit boxes above the diagram.
Repeat with different questions until you have mastered the method.
(If you are finding the questions difficult, use the pop-up menu under the Another question button to restrict the type of question until you have mastered the four different types. Then progress to answering random question types.)