Final answer:
A discrete random variable can only take on a countable number of values, while a continuous random variable can take on any value within a given range. In the given scenarios, the identified random variables are all discrete.
Step-by-step explanation:
A discrete random variable can only take on a countable number of values, while a continuous random variable can take on any value within a given range. Let's analyze each scenario:
(a) The random variable x represents the number of questions answered correctly on a 20-question examination. The values that x can assume are 0, 1, 2, ..., 20, so the random variable is discrete.
(b) The random variable x represents the number of cars arriving at a toll booth in 5 hours. The values that x can assume are 0, 1, 2, ..., 24, so the random variable is discrete.
(c) The random variable x represents the number of returns containing errors in 58 tax returns. The values that x can assume are 0, 1, 2, ..., 58, so the random variable is discrete.
(d) The random variable x represents the number of nonproductive hours in a seven-hour workday. The values that x can assume are 0, 1, 2, ..., 7, so the random variable is discrete.
(e) The random variable x represents the number of pounds in a shipment of goods. The values that x can assume are 0, 1, 2, ..., 16, so the random variable is discrete.