Which of the following random variables is geometric?
A) the number of phone calls received in a one-hour period
B) the number of cards I need to deal from a deck of 52 cards that has been thoroughly shuffled so that at least one of the cards is a heart
C) the number of digits I will read beginning at a randomly selected starting point in a table of random digits until I find a 7
D) all of the above
E) none of the above

Question

Quizplus · Accepted Answer

A geometric random variable represents the number of trials needed to achieve the first success, where the probability of success remains constant across trials. Option C fits this definition as we are counting the number of digits we need to read until we find a 7 which is the first "success". Options A and B do not fit the definition of a geometric random variable. Option A represents a Poisson distribution, and option B represents a hypergeometric distribution.

Which of the Following Random Variables Is Geometric