For this question think about two cases where the Target Population for a study is different from the Sample Population. In your first example, discuss a case where, although the two are different, it would be feasible to defend the idea that the inference from the sample population could be extrapolated to the target. In the second example, discuss a cases where it would not be feasible.
(1) I have heard that when companies want to "product test" new products, they will choose to do so taking a sample from a mid-western state like Ohio. Apparently, experience has led companies to believe that results from a product test in Ohio can generally represent the taste/preferences from the entire US.
Target population: US consumers
Sample population: Ohio consumers
(2) In my video I mentioned the example where a study was conducted on the demand for language classes among college students. In this case, the sample was taken from a rural, regional state university. I do not believe that the results from this sample would be able to really represent the results for college students nationally.
Target population: US college students
Sample population: College students at one particular regional university.