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Correct Answer counted wrong 7 times before accepted

Correct Answer counted wrong 7 times before accepted

by Mary Shepherd -
Number of replies: 3
This has appeared on the forum before but I didn't see a solution. Several students have reported that their answers that they KNEW were correct were counted wrong several times before being counted as correct. One such example from a student today was on this problem. I copied from the "editing" window so the library path could be seen. Her seed was 3655, and a copy of the answer log page is attached. The course path is http://webwork.nwmissouri.edu/webwork2/Precalculus_17-117_Shepherd_Fall_2013/HW_2-1/18/?effectiveUser=S517956&displayMode=images




In reply to Mary Shepherd

Re: Correct Answer counted wrong 7 times before accepted

by Davide Cervone -
The URL you give is to your course on your server, which we can't access. Can you tell us the path to the problem file as it appears in the Homework Set Editor, for example, or at the beginning of the problem when you view it as a professor? It should be something ending in ".pg". That way we can look at the problem and see what might be going on.

Also do you know what version of WeBWorK and PG you are using?

In reply to Davide Cervone

Re: Correct Answer counted wrong 7 times before accepted

by Mary Shepherd -
Davide,

Sorry. I knew better. The path to the problem file is:
Library/Rochester/setAlgebra14Lines/slope_from_pts_var.pg

If you need more examples, just let me know. I would say about half of my students have commented on this on different problems.

We are running WW v 2.7 and pg v 2.7.

Mary
In reply to Mary Shepherd

Re: Correct Answer counted wrong 7 times before accepted

by Davide Cervone -
Thanks for the extra info. I am not able to reproduce the problem (though I didn't really expect that I would).

What happens if your student submits the answer AGAIN? Is it marked right again? If she continues to submit, can you get it to be marked wrong again?

If you CAN get it to be marked wrong, then could you edit the problem and change

    ANS(fun_cmp($A*$C,var=>['h']));
to
    ANS(fun_cmp($A*$C,var=>['h'],diagnostics=>1));
and submit the problem until it fails to be marked correct. You should get some graphs and data at the bottom of the problem. Could you send me the data from the table below the graphs? (It should give the values of h used in the answer checking, plus the correct and student answers and the relative and absolute errors.)

The problem is written in a very old (pre-MathObjects) style, and it uses fun_cmp even though the value is a number (presumably so that if the student enters answers that include h there is no error message). The problem should really be rewritten to use MathObject in Point context, but that is another matter.

Because fun_cmp is used, the problem compares the numbers as functions, and so produces several test points, and it seems that one or more of these is not matching for some reason (though I can't for the life of me think of why -- that is why I need the diagnostics output).

Finally, do you have anything in your course templates/macros directory?

Let's hope we can track this down.