MediumProbabilitypr-350

Negative Binomial PMF Value

Problem

For the number of failures K before the r-th success, P(K = k) = C(k + r - 1, k) (1 - p)^k p^r.

Given r, p, and k, return the probability.

Hint

The last trial is a success; the rest array r - 1 successes among k failures.

case 1

in: [2,0.5,1]

expected: 0.25

case 2

in: [1,0.2,3]

expected: 0.10240000000000003

case 3

in: [3,0.6,0]

expected: 0.21599999999999997

Starter codePython

def negative_binomial_pmf_value(r, p, k):
    # Your code here
    pass

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