There is a template for the chapter's practice. You can find my (maybe wrong) solution in solutions/ folder, but remember it will be more fun to try to solve them yourself.

using Distributions
using StatsPlots
using StatsBase
using StatisticalRethinking

Easy problems

Code 3.27

size = 1000
p_grid = range(0, 1; length=size)
prob_p = repeat([1.0], size);
prob_data = [pdf(Binomial(9, p), 6) for p in p_grid];
posterior = prob_data .* prob_p
posterior /= sum(posterior);
cat = Categorical(posterior)
samples = p_grid[rand(cat, 10000)];

Medium problems

Hard problems

Code 3.28

birth1 = [1,0,0,0,1,1,0,1,0,1,0,0,1,1,0,1,1,0,0,0,1,0,0,0,1,0,
0,0,0,1,1,1,0,1,0,1,1,1,0,1,0,1,1,0,1,0,0,1,1,0,1,0,0,0,0,0,0,0,
1,1,0,1,0,0,1,0,0,0,1,0,0,1,1,1,1,0,1,0,1,1,1,1,1,0,0,1,0,1,1,0,
1,0,1,1,1,0,1,1,1,1]

birth2 = [0,1,0,1,0,1,1,1,0,0,1,1,1,1,1,0,0,1,1,1,0,0,1,1,1,0,
1,1,1,0,1,1,1,0,1,0,0,1,1,1,1,0,0,1,0,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,0,1,1,0,1,1,0,1,1,1,0,0,0,0,0,0,1,0,0,0,1,1,0,0,1,0,0,1,1,
0,0,0,1,1,1,0,0,0,0];

Code 3.30

sum(birth1) + sum(birth2)

111