import scipy as sp

X = sp.stats.expon(scale = 1.1)

p = X.cdf(2) - X.cdf(1)

0.24056971034728492

There’s a p percent chance that someone is infectious between one and two days.

1 - X.cdf(1.5)

0.25572915991310063

X.ppf(.9)

2.532843602293451