# binomial distribution

This seems like it should be an easy one but I don’t get why “D” is not a valid answer: Which of the following could be the set of all possible outcomes for a random variable that follows a binomial distribution? A) (-1, 0, 1). B) (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11). C) (0, 0.5, 1, 1.5, 2, 2.5, 3). D) (1, 2). The correct answer was B) (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11). This reflects a basic property of binomial outcomes. They take on whole number values that must start at zero up to the upper limit n. The upper limit in this case is 11.

D is not valid because it does not start at 0. C does, but it is not made solely of whole numbers… Hence B is the answer.

A has -1 in it. So not binomial. C has 0.5, etc. etc. D doesn’t have 0.

Suppose I toss the coin 5 times… Each trial has outcome head / tail – > Binomial distribution My experiment is - number of heads in 5 trials Now you could have 0 heads (All 5 tails) you could have 1 heads ( 4 tails) … … you could have 5 heads ( 0 tails) All possible outcomes are 0,1,2,…5. HTH !

Got it! My brain is fried. Thanks all.