In a study of weight gains by college students in their freshman year, researchers record the amounts of weight gained by randomly selected students (as in Data Set 6 "Freshman 15" in Appendix B). Is the data from a discrete or continuous data set?

For this particular case they are interested on the amount of weight gained by randomly selecting some students, we need to remember that the weight can't be a discrete random variable since this random variable can take values on a specified interval and with decimals, so for this case the best conclusion is that we have a continuous data set.

Step-by-step explanation:

Previous concepts

We need to remember that continuous random variable mans that the values are specified over an interval in the domain, so is possible to have decimal values for the possible outcomes of the random variable.

By the other hand a discrete random variable only can take integers for the possible outcomes of the random variable over the specified domain.

Solution to the problem

For this particular case they are interested on the amount of weight gained by randomly selecting some students, we need to remember that the weight can't be a discrete random variable since this random variable can take values on a specified interval and with decimals, so for this case the best conclusion is that we have a continuous data set.