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# Probability questions about students in various classes

4. Of the 47 people who answered "yes" to a question, 8 were male. Of the 100 people who answered"no" to the question, 12 were male. If one person is selected at random from the group, what is the probability that the person answered "yes" or was male?
A) 0.456
B) 0.401
C) 0.136
D) 0.17

5. A teacher designs a test so a student who studies will pass 95% of the time, but a student who does not study will pass 8% of the time. A certain student studies for 85% of the tests taken. On a given test, what is the probability that student passes?
A) 0.12
B) 0.82
C) 0.515
D) 0.808

6. The following table shows the grades of college students in an advanced mathematics course,broken down by year.
Use the table below to find the probability that a randomly selected sophomore gets a B.

A B C D E Totals (%)
Freshmen 3 5 6 4 1 19
Sophomores 6 3 8 2 3 22
Juniors 5 7 15 6 2 35
Seniors 5 4 1 2 5 17
Grad Students 3 2 2 0 0 7

Totals (%) 22 21 32 14 11 100

A) 1/11
B) 3/22
C) 1/7
D) 4/21