2009 ADA test math question #22

[blankman321]

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to anyone that has the 2009 ADA test, isnt the answer supposed to be 56/132, the answer key says 16/33

here's I came up with the answer:

(8/12) x (7/11) = 56/132

 

[blankman321]

bump anyone, have my exam in a couple of hours, really like to know if I am doing this right or wrong?

 

[DenTony11235]

bump anyone, have my exam in a couple of hours, really like to know if I am doing this right or wrong?

Post the question and multiple choices man, I'd gladly have a look.

 

[Illfavor]

One red, not two.

To explain better: 8 reds, 4 whites. There are two ways to pull just one red ball: red then white, or white then red. So:

(8/12) x (4/11) x 2 = 64/132 = 16/33

 

[blankman321]

Illfavor thanks so much, I was focused on the total number of the red balls that I failed to consider the white balls (hence my 7/11 instead of 4/11 part), thanks so much!