Betsy is testing whether school is more enjoyable when students are making high grades. she asked 150 students if they enjoyed school and whether their gpa was above or below 3.5. she found that 35 of the 60 students with a gpa above 3.5 reported that they enjoyed school, and 15 of the 90 students with a gpa below 3.5 reported that they enjoyed school. what is the probability that a student with a gpa below 3.5 does not enjoy school?

The probabiility that  a student with a GPA below 3.5 enjoys school is 15/90 = 1/6.
probability a student get a GPA below 3.5 doesn't enjoy school is: 1-1/6 = 0.83.

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Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.