mu = 120
sigma = 9.5 (slider from 2.5 to 25, step 0.1)
phi(x) = exp((-((x - mu) / sigma)^(2)) / 2) / (sigma * sqrt(2 * 3.141592653589793))
a = 60 (slider from 60 to 180, step 1)
b = 127 (slider from 60 to 180, step 1)
A: (a, phi(a))
B: (b, phi(b))
H: (a, 0)
K: (b, 0)
c = Segment(H, A)
d = Segment(K, B)
Prob = Integral(phi, a, b)
e = Integral(phi, -5, a)
f = Integral(phi, b, 5)