I am creating a small piece of software to help with mental arithmetic.
In a first level there will be numerical questions, something like "what is roughly 6 / 9.5?" and the user should get multiple choice to answer. The questions itself are dynamic. The correct answer obviously is trivial to receive (63%, or even round it to 65%), but how can I create false multiple choice answers dynamically that aren't totally easy to dismiss, but also not too close to the correct answer.
A specific example of a result I want: Q: what is roughly 6 / 9.5?
A1: 50% A2: 75% A3: 65%
What I don't want is something like this:
A1: 5% A2: 10% A3: 65%
So I guess I want a range (which I probably have to define somehow domain wise) of possible answers depending on the level, because later on answers like A1: 60%, A2: 63%, A3: 67% might be a good challenge.
Is there any sort of "algorithm" so get to useful false answers?