Chapter 3 exercise on socks - question and answers not aligned about thinkbayes2 HOT 2 CLOSED

I agree with your statement, the solution provided in the book doesn't make sense in my head.

In my opinion, it's clearer to state the possible outcomes we are expecting and to follow the choosing of the socks step by step:

# K is black
prior = Pmf(1 / 5, ['WW', 'KK', 'RR', 'GG', 'BB'])
likelihood = [1 / 2, 1 / 2, 1 / 3, 1 / 3, 1 / 3]

# draw the first sock
pmf = prior * likelihood
pmf.normalize()
pmf['WW'] # 0.25

# draw the second sock
pmf = pmf * likelihood
pmf.normalize()
pmf['WW'] # 0.3

from thinkbayes2.

I believe the answer in the book is correct under the assumption stated in the problem "For simplicity, let’s assume that there are so many socks in both drawers that removing one sock makes a negligible change to the proportions."

This assumption is not super realistic, but it is intended to simplify the problem so it can be solved by applying the methods in the chapter.

The solution has two steps: first, figuring out the probability that the socks were drawn from the drawer with black and white socks, and then the probability that the socks are white if they were drawn from the black and white drawer.

from thinkbayes2.