A random variable is defined as a process or variable with a numerical outcome. Which of the following are random variables? i. The amount of rain, in inches, that will fall next Friday in Dallas, TX.
ii. The major of a randomly drawn student from Arizona State University.
iii. The number of books purchased next year by your local library.

a. i only
b. ii only
c. iii only
d. i and iii
e. ii and iii
f. i, ii, and iii

d. i and iii

Step-by-step explanation:

Notice that the definition provided states that the outcome needs to be numerical in order for a variable to be deemed a random variable:

i. The amount of rain is described in inches (i.e. 1.5 in; 2.0 in) and thus may be considered a random variable

ii. The major of a student is not quantitative as it is a descriptive variable (i.e. Arts; Psychology) and thus is not a random variable

iii. The number of books purchased is a numeric quantity (i.e. 15 books) and may be considered a random variable

Therefore, the answer is d. i and iii