What kinds of sampling designs would be used for the following cases and why? Please, provide an explanation.
1. A study to get a quick idea of the medical acceptability of a new aspirin substitute which cannot be dispensed over the counter without prescription.
2. A study involving a sample of 325 students in a university where 2,000 students are enrolled (both with and without replacement).
3. An investigation of the career salience of professionals in the fields of medicine, engineering, business, and law.