Expert: Lynn Houston - 12/17/2008

Question
Word Problem:  Aaron has 9 new pencils. 4 of them are not red, 3 of them are blue, and 2 of them are yellow. What fraction of the pencils are NOT red?  4/9 was selected as an answer but it was marked wrong.

Answer
Tricky question.  This is a matter of really reading the question well.  Assuming that he only has Red, Blue and Yellow pencils, you know that at least 5 are not red because 3 are blue and 2 are yellow, therefore, either none of them are red (if the statements are mutually exclusive) or 5 of them are not red and the statement "4 of them are not red" is included in the 5 that you already know about (3 blue and 2 yellow).  So, depending on your assumptions, the answer is either 9/9 (all of them are not red) or at least 5/9 (those that you definitely know are blue and yellow).