I am attempting to create a formula that takes the decimal odds of there being under 2.5 goals in a soccer match, and returns the estimated number of goals based on this. So far though, I have only been able to do the opposite - when the estimated number of goals are input, it produces the odds of them occurring. In Excel, it is:
=1/POISSON (2, number of goals,1)
Is there any way to reverse this, so that the odds are the input, and the expected goals are the output?