p = 0.5 (slider from 0 to 1, step 0.1)
q: 1.0 - p
n = 15 (slider from 0 to 1050, step 1)
bin = Sequence(Binomial[n, k] * p^(k) * q^(n - k), k, 0.0, n)
k = 3 (slider from 0 to 50, step 1)
a = Min(k, n)
l = 4 (slider from 0 to 50, step 1)
b = Min(n, k + l)
Flächen = Sequence(Polygon[(k - 1.0, 0.0), (k, 0.0), (k, Element[bin, k]), (k - 1.0, Element[bin, k])], k, a + 1.0, b + 1.0)
P = Sum(Flächen)
binVert = Sequence(Polygon[(k - 1.0, 0.0), (k, 0.0), (k, Element[bin, k]), (k - 1.0, Element[bin, k])], k, 1.0, n + 1.0)
Text1: "P(" + a + " ≤ X < " + (b + 1.0) + ") = " + P
Text2: "a = " + a
Text3: "b = " + (b + 1.0)