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# If you select a student at random, what is the probability that the student has gone to...

duer1234 | Student, Undergraduate | eNotes Newbie

Posted January 11, 2009 at 1:25 AM via web

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If you select a student at random, what is the probability that the student has gone to the beach but not to the amusement park?

Suppose that among all U.S students, 80% have gone to an amusement park and 45% have gone to the beach. Only 15% have done neither.

mcetner | High School Teacher | (Level 1) Adjunct Educator

Posted February 6, 2009 at 9:22 PM (Answer #1)

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If you know there are 100% of people to chose from, and 15% have done neither, then you have 85% left. Since 80% have gone to an amusement park, only 5% have not.  These 5% have gone to the beach only.  The breakdown would be as follows:

neither: 15%

beach only: 5%

amusement park, only: 40%

both: 40%

revolution | College Teacher | Valedictorian

Posted July 21, 2010 at 10:10 PM (Answer #2)

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There's 100% of students to choose from. Since you know that 15% of them did not do either of these places, then 85% of them might have gone to the beach or the amusement park.

Since you know that 80% of the students went to the amusement park, only 5% of them didn't, so they must have went to the beach.

The P(students went to beach is 5/100= 1/20

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