Exponential Moments Mean Variance

Problem

The exponential distribution with rate lambda has mean 1 / lambda and variance 1 / lambda^2.

Given the rate, return [mean, variance].

Hint

Both moments are powers of the reciprocal rate.

case 1

in: [2]

expected: [0.5,0.25]

case 2

in: [0.5]

expected: [2,4]

case 3

in: [10]

expected: [0.1,0.01]

Starter codePython

def exponential_moments_mean_variance(rate):
    # Your code here
    pass

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