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Topic: Rubric for A2&T #38
Replies: 7   Last Post: Jun 22, 2011 8:09 PM

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 Virginia Kuryla Posts: 60 Registered: 1/26/06
Re: Rubric for A2&T #38
Posted: Jun 22, 2011 9:44 AM
 att1.html (4.0 K)

I put 17/81 into the scientific calculator on the computer and got 0.20987654320987654320987654320988, so they would have to acknowledge that 0.209876543 is the part that repeats. The 2 on the end is the beginning of the next section.

>>> <TKENYON@crcs.wnyric.org> 6/22/2011 8:23 AM >>>

I think the loss of one point implies that the student did not realize that it was a repeating decimal. If a student wrote the fraction as a repeating decimal, then I see no reason to not award full credit. But, if they wrote it as a terminating decimal, then they deserve to lose the point. It says "exact value," not "rounded to the nearest ten billionth (or whichever place, depending on how many digits are on their display.)

-Tom Kenyon
CRCS Mathematics/Physics
tkenyon@crcs.wnyric.org

-----owner-nyshsmath@mathforum.org wrote: -----

To: nyshsmath@mathforum.org
From: Jennifer Sauer
Sent by: owner-nyshsmath@mathforum.org
Date: 06/22/2011 07:04AM
Subject: Rubric for A2&T #38

While I do have problems with other questions on the test, #38 is actually a fair, predictable question. The problem involves binomial probability, and the answer is is 51/243 or 17/81. This fraction is equivalent to .2098765432. The rubric says if a decimal answer is given, the students can only receive 3 out of 4 points. I would agree if the student rounded the decimal to .2099 for example.
Since .2098765432=17/81, it should also be an exact answer. If the answer to a question was 1/2 would we not accept .5?

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Date Subject Author
6/22/11 Jennifer Sauer
6/22/11 JFish@csufsd.org
6/22/11 Jennifer Sauer
6/22/11 Jennifer Sauer
6/22/11 Tom Kenyon
6/22/11 Virginia Kuryla
6/22/11 Eleanor Pupko