Hypergeometric Moments Mean Variance

Problem

For n draws without replacement from N items with K successes, mean = n K / N and variance = n (K / N)(1 - K / N)(N - n) / (N - 1).

Given N, K, and n, return [mean, variance]. Assume N > 1.

Hint

The finite population correction shrinks the binomial variance.

case 1

in: [10,4,3]

expected: [1.2000000000000002,0.56]

case 2

in: [20,10,5]

expected: [2.5,0.9868421052631579]

case 3

in: [100,25,10]

expected: [2.5,1.7045454545454546]

Starter codePython

def hypergeometric_mean_and_variance(n_population, k_successes, n_draws):
    # Your code here
    pass

3 test cases · run your code against them in the editor