e = 2.718281828459045
c = 0.12 (slider from 0 to 2, step 0.0010)
Endmonat = 12 (slider from 1 to 60, step 1)
f(x) = c * e^(-c * x)
Startmonat = 3 (slider from 0 to 13, step 1)
a = UpperSum(f, Startmonat, Endmonat, Endmonat - Startmonat)
b = LowerSum(f, Startmonat, Endmonat, Endmonat - Startmonat)
F(x) = -exp(-c * x)
d = Integral(f, Startmonat, Endmonat - 1.0)
Wahrscheinlichkeit: F(Endmonat - 1.0) - F(Startmonat)