How it works: The calculator above allows students to compute probabilities based on exponential distributions. The calculator can be used in two ways. To find Prob > x, enter the value of x in the "Area right of" box and hit "Compute!". The answer is given in the "=" box. To find an x for a probability, enter a value under in the "=" box and hit "Compute!". The x value is given in the "Area right of" box. In each case the graphic provides a visual display of the probability.