Question

d. is the time it takes for a light bulb to burn out a discrete random variable, a continuous random variable, or not a random variable?
a. it is a continuous random variable.
b. it is a discrete random variable.
c. it is not a random variable.
e. is the number of textbook authors now sitting at a computer a discrete random variable, a continuous random variable, or not a random variable?
a. it is a discrete random variable.
b. it is a continuous random variable.
c. it is not a random variable.
f. is the time required to download a file from the internet a discrete random variable, a continuous random variable, or not a random variable?
a. it is a continuous random variable.
b. it is a discrete random variable.
c. it is not a random variable.

Explanation:

• Discrete random variable: A discrete random variable has a countable number of possible values. For example, the number of textbook authors (e - it can be counted as 1, 2, 3...).
• Continuous random variable: A continuous random variable can take on any value within a certain interval. The time it takes for a light bulb to burn out (d - it can be any value within a range, like 100.5 hours, 200.3 hours etc.) and the time required to download a file from the Internet (f - it can be 10.2 seconds, 15.7 seconds etc.) are continuous as they can take an uncountable number of values within a range.

Answer:

d. C. It is a continuous random variable.
e. A. It is a discrete random variable.
f. B. It is a continuous random variable.