Question

What is variance of a geometric distribution having parameter p=0.72?

(a) 54%

(b) 76%

(c) 13%

(d) 69%

I had been asked this question during an interview.

The origin of the question is Geometric Probability in portion Discrete Probability of Discrete Mathematics

Answer 1

Correct choice is (a) 54%

The best I can explain: The variance of a geometric distribution with parameter p is \(\frac{1-p}{p^2} = \frac{(1-0.72)}{0.722}\) = 0.54 or 54%. However, the variance of the geometric distribution and the variance of the shifted geometric distribution are identical.