A researcher at Florida International University (FIU) wants to estimate the average number of credits earned by students last semester at FIU. She randomly selects 750 students from last semester and finds that they averaged 13.75 credits per student. The population of interest to the researcher is: a) all FIU students ervoled last semester. b) all FIU students c) the 750 FIU students selected at random. d) all college students.

Step-by-step explanation: The population of interest is defined as the population that you are drawing an inference (or conclusion) about. Usually, you cannot obtain the data for the whole population of interest, rather you can only obtain data for a proportion of it and then make inference about the whole population.

In this question, we can see that the researcher considers the population of interest to be "students last semester at FIU", therefore, A is the best answer. Option B and D are too broad, while option C refers to the sample, not population of interest, of the study.