import numpy as np
import matplotlib.pyplot as plt
import scipy as sp

X = sp.stats.norm(loc = 95, scale = 5)

# a
X.cdf(100) - X.cdf(90)

0.6826894921370859

# b
1 - X.cdf(105)

0.02275013194817921

# c
X.cdf(80)

0.001349898031630093

# d
X.ppf(.975)

104.79981992270027