(a) Compare the proportion of students who use a Windows-based PC to the proportion who use a Mac.
(b) Compare the proportion of students who study abroad between those attending public universities and those at private universities.
(c) Compare the proportion of in-state students at a university to the proportion from outside the state.
(d) Compare the proportion of in-state students who get financial aid to the proportion of out-of-state students who get financial aid.

Situations comparing two proportions are described. In each case, determine whether the situation involves comparing proportions for two groups or comparing two proportions from the same group. State whether the methods of this section apply to the difference in proportions.