Which program to solve integration = 0 for a variable?

Question

i'd like to know how to solve a definite integral in Mathematica.

I do know all variables except b, and need to solve for F(b)=0.

How can i solve it in Mathematica?

Here is my try:

 NSolve[Integrate[1/(8*(1 - ff) (2 Pi)^0.5) E^(-0.5*((x - 1.1)/(1 - ff)/8)^2), {x, 0, 9999}] == -0.44531779637243296, ff]

Answer 1

These integrals can be trivially expressed in terms of an error function: Wiki, Mathworld. Hence what you need here is a library to (i) calculate error functions, (ii) numerically solve non-linear equations. Virtually any language has this, so pick anything you're familiar with. In Mathematica, look up Erf and NSolve.