SOLUTION: In a high school graduating class of 100 students, 54 studied mathematics, 69 studied biology and 35 studied both mathematics and biology. If one of these students is selected at

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Question 1172477: In a
high school graduating class of 100 students, 54 studied mathematics, 69 studied biology and 35 studied both mathematics and biology. If one of these students is selected at random, find the probability that the student:
i. Took mathematics or biology
ii. Did not take either of these subject
iii. Took biology but not mathematics
Answer by ikleyn(52756) About Me  (Show Source):
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In a high school graduating class of 100 students, 54 studied mathematics, 69 studied biology and 35 studied
both mathematics and biology. If one of these students is selected at random, find the probability that the student: 

i. Took Mathematics or Biology               54 + 69 - 35 = 88 studied both subjects;
                                             THEREFORE, the probability  P = 88%2F100 = 0.88.    ANSWER



ii. Did not take either of these subject     100 - 88 = 12 did not study any of the two subjects.

                                             THEREFORE, the probability  P = 12%2F100 = 0.12.    ANSWER


iii. Took Biology but not Mathematics        69 - 35 = 34 studied B but not M. THEREFORE, the probability  P = 34%2F100 = 0.34.    ANSWER

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    - Counting elements in sub-sets of a given finite set
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