Can someone me with problems 3, 4, and 5?

3. i'm not entirely sure about this one, because i feel like i'm making it more complicated than it is, but if there are 100 students and 80% of them would know the answer--80% of 100 is 80. therefore, 80 students would pass and 20 would fail.

4. if you're sending someone an e-mail... the only way to check an email is through the web, so they'll get a 100% "yes i use the web" response because they only sent the survey through e-mail

5. very few, if not absolutely none of the students who received As would ask for a grade re-evaluation. most people are satisfied with As and they'd be scared that, if re-evaluated, their grade would drop. they likely wouldn't respond to the dean in the affirmative.