For example, I want 4 successes out of 7 trials to yield a 95% answer, meaning I need to itterate on the "P" input in the formula [=BINOMDIST(4,7,"P",TRUE) should result in .95]. Using solver it iterates successfully to .3413.

Now, change 4 to 6, and solver drives "P" to an answer that causes a #NUM result (P= 4.023), however I can manually input 0.6518 and I get the right answer.

I've tried adding constraints that won't let the input go outside the bounds of 0 and 1.0 but it does anyway.

Ideas?