Janet wanted to understand whether grade level had any relationship to their opinion on extending the school day. She surveyed some students and displayed the results in the table below: In favor Opposed Undecided Grade 9 4 2 8 Grade 10 7 11 8 Grade 11 14 15 9 Grade 12 11 5 10 Compare P(Grade 9 | opposed) with P(opposed | Grade 9).
Above is a partial sum chart that will help us in our quest.
P(Grade 9 | opposed) The probability of Grade 9, given opposed, is the portion of opposed students that are in grade 9. Total number opposed: 33 Number opposed in Grade 9: 2 P(Grade 9 | opposed) = 2 / 33 = 0.06
P(opposed | Grade 9) Total Number Grade 9: 14 Number opposed in Grade 9: 2 P(opposed | Grade 9) = 2 / 14 = 0.14