Formulas: More examples
Significant figures
"The significant figures of a number are digits that carry meaning contributing to its measurement resolution." (Reference: https://en.wikipedia.org/wiki/Significant_figures).
The Formulas question has no built-in function to display numbers with a given number of significant figures. However, it is easy to work out this function as the following variable assignment which works with any real number:
xr=x==0?x:round(x*pow(10,nsf-1-floor(log10(abs(x)))),0)*pow(10,-nsf+1+floor(log10(abs(x))));
where x is the number to be rounded, nsf the number of significant digits to keep and xr the resulting rounded value.
This example deals with the display of the correct answers with different numbers of significant figures.
The Formulas question should look like this:
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This example is a significant figures drill.
General
Question name* Significant figures drill
Variables
Random variables a=a={-1,1};
b={-4:4.01:0.01};
ncs={2,3,4};
Main question
Question text* With part's text placeholders
Two subquestions on addition:
{#1a}
{#1b}
One subquestion on subtraction:
{#2}
Part 1
Part's mark* 1
Answer type Number
Answer* 7
Grading criteria* Absolute error == 0
Placeholder name #1a
Part's text What is 3 + 4?
Part 2
Part's mark* 1
Answer type Number
Answer* 9
Grading criteria* Absolute error == 0
Placeholder name #1b
Part's text What is 4 + 5?
Part 3
Part's mark* 1
Answer type Number
Answer* 3
Grading criteria* Absolute error == 0
Placeholder name #2
Part's text What is 9 − 6?
The Formulas question should look like this:
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