QUIZ 1 & 2

1) What is a discrete probability distribution?

• • A) A distribution that describes the likelihood of each possible outcome for a discrete random variable

• • B) A distribution that describes outcomes for continuous variables only

• • C) A distribution that includes only negative values

• • D) None of the above

2) Which of the following is NOT a characteristic of a binomial distribution?

• • A) Fixed number of trials

• • B) Only two possible outcomes for each trial

• • C) Each trial is independent

• • D) Number of successes is fixed

3) If X is a discrete random variable, which of the following defines its probability mass function (pmf)?

• • A) P(X=x) > 1 for all x

• • B) The sum of all P(X=x) is less than 1

• • C) P(X=x) = 1 for all x

• • D) The sum of all P(X=x) is equal to 1

4) Variance of binomial distribution___

• p

• np

• npq

• n

5) Which distribution is used to model the number of events occurring within a fixed interval of time or space?

• Binomial

• Normal

• Exponential

• Poisson

6) In a Poisson distribution, the mean and variance are:

• • A) Equal to each other

• • B) Completely unrelated

• • C) Mean is always greater than variance

• • D) Variance is always greater than mean

7) What is the key difference between a Poisson distribution and a binomial distribution?

• • A) Binomial is for discrete outcomes; Poisson is for continuous outcomes

• • B) Binomial has a fixed number of trials, while Poisson does not

• • C) Poisson distribution applies only to very large samples

• • D) They are the same distribution

8) Which of the following distributions is appropriate for counting the number of trials until a success?

• • A) Poisson distribution

• • B) Binomial distribution

• • C) Geometric distribution

• • D) Uniform distribution

9) For a hypergeometric distribution, the probability of success changes in each trial because:

• • A) Each trial is dependent on the previous trial

• • B) The trials are independent

• • C) Each trial has a fixed probability of success

• • D) None of the above

10) In a geometric distribution, what does the random variable X represent?

• • A) The total number of successes in a fixed number of trials

• • B) The number of trials until the first success

• • C) The sum of probabilities for each trial

• • D) The number of failures until the first success