Significant figures



  • I am using Mobius to test student's ability to use simple equations such as power = energy / time with numerical questions. (This is on a foundation year program.) I use two significant figures to compare their results to the correct answer. One issue is that if 500 is the correct answer, then Mobius assessment regards this as correct to one significant figure and marks it wrong. The correct answer is 5.0E2 to two significant figures. After looking at the web, this is viewed as the correct way to compute significant figures, although there is no way I am going to teach the students this. Is there any way to better compare significant figures, other than to include more digits in the random variables?


  • administrators

    Hi cmcneile,

    One solution to this would be to hold the answer in a variable. For example to calculate power = energy/time we could use variables such that $P = $E/$T. In the response area (assuming you are using numeric) you can then set "Required with" to "absolute accuracy". If you are using randomisation such that $P would be to more than two significant figures you can use the command "decimal(n,x)" in the algorithm section where x is the input and n is the number of decimal places. In this case it would be decimal(2,$P).

    Hope this helps.


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