Homework Help

There are 7 mysteries, 9 biographies, 2 reference books,and 10 picture books in the...

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maganda123 | (Level 1) Honors

Posted November 16, 2008 at 1:37 PM via web

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There are 7 mysteries, 9 biographies, 2 reference books,and 10 picture books in the book bin at the library.

What are the odds of drawing a mystery book from the bin?

please help me answer this question.

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plfoster | High School Teacher | eNotes Newbie

Posted November 17, 2008 at 12:45 AM (Answer #1)

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1 in 4....There are 28 books total...there are 7mysterys to the 28 total....so your chances of drawing a mystery would be 7 in 28 if it is reduced it would be 1 in 4.

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cburr | Middle School Teacher | (Level 2) Associate Educator

Posted November 17, 2008 at 7:16 AM (Answer #2)

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To figure out the probability (odds) of something happening, what you have to do is count up ALL the possibilities, and then count up how many of them involve the result you are looking for.

In this case, there are 28 different books, so there is a total of 28 possibilities of what book will be drawn from the bin.   Since 7 of the books are mysteries, 7 out of the 28 possibilities will be mysteries.  From a math standpoint, this is 7:28 or 7 out of 28.  Since 7 goes evenly into 28 (4 x 7 = 28), you can reduce it to 1:4 or 1 out of 4.  

It is important to remember that the probability is what would happen on average if you tried it many, many times.  You can't be sure that 1 of the first 4 books you actually pull on one try will be a mystery.  1 out of 4 is just the probable result.

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neon-ice-cream | Student, Grade 9 | (Level 1) Honors

Posted January 11, 2009 at 12:16 AM (Answer #3)

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revolution | College Teacher | (Level 1) Valedictorian

Posted July 17, 2010 at 6:20 PM (Answer #4)

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There are 7+9+2+10=28 books in total, and there are only 7 mystery books,

P(mystery books)= 7/28=1/4 (simplified form).

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mrschamp | Elementary School Teacher | eNotes Newbie

Posted November 22, 2010 at 4:08 AM (Answer #5)

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You need to find the total of the books.  Add the following 7 + 9 + 2 + 10 and you get 28.  Then you need to look at the problem and see that there are 7 mystery books.  Probability is written in fractions.  The numerator (top number) is the number of mystery books.  The denominator is the total number of books.  That makes you have the fraction 7/28.  You reduce that to 1/4.

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