Question

Which of the following is a continuous random variable?

Answer 1

Answer: B) The time to complete a specific task.

For any two different time values, it is possible to find the midpoint or average of them. For instance, if it takes 10 minutes to do the task on Monday, and then 11 minutes to do the task on Tuesday, then it takes (10+11)/2 = 21/2 = 11.5 minutes to do the task on average. Because we are able to find a midpoint like this, and a decimal midpoint makes sense, this means time is a continuous variable.

In contrast, the number of new hires must be a whole number. If we had 10 hires on Monday and 11 hires on Tuesday, then it doesn't make sense to say we hired 11.5 people. So choice A is ruled out. Similar situations play out with choices C and D, which is why we can rule those out too. Choices A, C and D are discrete variables.