Question

1) Which of the following statements is correct (circle one answer)? A. A random variable is a subset of the sample space. B. The expected value of a random variable measures the variability of the random variable. C. If a discrete random variable has three possible values 1, 2, and 3, then its expected value has to be one of these three values. D. If the set of possible values of a random variable is {-17, 0, 1.4, 5000} then it is a discrete random variable

Answer 1

D. If the set of possible values of a random variable is {-17, 0, 1.4, 5000} then it is a discrete random variable

The above statement is correct. The random variable can only take the 4 value given above. It cannot have any other values in between, making it discrete.

A is wrong because, a value that a random variable can assume is a subset of sample space, but the random variable itself is not a subset of sample space.

B is wrong because expected value is not a measure of variability. It is a measure of central tendency

C is wrong because the expected value can be any value between 1 and 3 in this case.