Question

The table shows the percentage of students in each of three grade levels who list soccer as their favorite sport. Soccer Sophomores (35%) 50%
Juniors (33%) 45%
Seniors (32%) 30%
Total (100%) (0.5)(0.35) + (0.45)(0.33) + (0.32)(0.3) = 0.4195 or about 42%
Find the probability that the student is a junior, given that soccer is the favorite sport listed.
P(junior | soccer) = ???%

Answer 1

The answer should be roughly 35.4%. 

You can obtain this answer by looking at the percentage of each subgrouping. For instance, 33% of the class in juniors and 45% of them list soccer as their favorites. Thus showing that 14.85% of the entire school is made up of juniors that enjoy soccer. 

If you do the totaling for all soccer lovers, you get a total of 41.95% of the school. By dividing the two numbers you get the answer above.