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In a class, there are 12 boys and 16 girls. One of them is called out by an enroll number, what is the probability that the one called is a girl?
- A1/4
- B2/5
- C4/7
- D5/12
Correct answer: C
Discussion 1
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CCommunity
4/7
Let S be the sample space.
Total number of students in the class = 12 boys + 16 girls = 28.
Then, n(S) = 28.
Let E be the event of calling one of them by enroll number.
Given that, number of girls = 16.
Then, n(E) = 16.
The probability that the one called is a girl = n(S)/n(E) = 16/28 = 4/7.
Let S be the sample space.
Total number of students in the class = 12 boys + 16 girls = 28.
Then, n(S) = 28.
Let E be the event of calling one of them by enroll number.
Given that, number of girls = 16.
Then, n(E) = 16.
The probability that the one called is a girl = n(S)/n(E) = 16/28 = 4/7.