Question

When an opinion poll calls landline telephone numbers at random, approximately 30% of the numbers are working residential phone numbers. the remainder are either non-residential, non-working, or computer/fax numbers. you watch the random dialing machine make calls. x is the number of calls until the first working residential number is reached. does x have a binomial distribution? give your reasons?

Answer 1

A Binomial Distribution is a probability distribution where there exist two mutually exclusive outcomes, the probability of each outcome is constant, and the trials are independent. In this case the phone numbers are either working residential or not - two distinct choices. The probability is given as a fixed 30%. Lastly the success of each call has no bearing on the next call thus each dial is independent.