Question

In a political science class of 35 students, 21 favor abolishing the electoral college and thus electing the President of the United States by popular vote. If two students are selected at random from this class, what is the probability that both of them favor abolition of the electoral college? Draw a tree diagram for this problem.

The textbook answers this problem with .3529

From my understanding I should multiply 14/35 * 13/34 = .15

Where does .3529 come from?

Answer 1

Total number of students in a foolitical science clase is 35. Two students can be chosen from these 35 students in 35 ways. It is geven, among 35 students 21 students favor abolition of the electoral college. Two students can be chosen from these 21 students in ale ways. So, the probability that both the selected students favour abolition of the electoral college = aleg = 210 = 0.3529. 595 (35 34 [ The answer cannot be ( 14 * 13 ) = 0°15. As, the required probability concerns with the students who favor abolition of the electoral college. So, the two studants should be chosen from the 21 students who favor abolition of the electoral college. On the other hand, the two students should not be chosen from [35-21)=14 students who do not favore abolition of the electoral college. Again in the question, it is given that two students are selected at random, so order doesn't matter here.]