To overlay two probability distribution plots
main topic     example     see also 

1    Choose Graph > Probability Distribution Plot > choose Two Distributions> OK.

2    From Distribution 1, choose a distribution.

3    Enter one parameter per box. The specific parameters change depending on the distribution you choose.

4    From Distribution 2, choose a distribution.

5    Enter one parameter per box. The specific parameters change depending on the distribution you choose.

6    If you like, use any dialog box options, then click OK.