What if an exercise wasn't uniquely defined?

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Discussion Overview

The discussion revolves around the interpretation of a math exam question regarding the ratio of two wheels on a penny-farthing bike, specifically addressing the ambiguity in the question that led to different types of answers from students. The scope includes conceptual clarification and debate over the appropriateness of various interpretations of the question.

Discussion Character

  • Debate/contested, Conceptual clarification

Main Points Raised

  • Some participants argue that the question was ill-defined, leading to multiple interpretations, such as the ratio of radii versus the ratio of areas.
  • One participant suggests that the examiner should accept both types of answers due to the ambiguity in the question.
  • Another participant contends that the phrase "revolutions made along a certain distance" implies that the ratio of circumferences (and thus radii) is what was intended, as nothing in the question indicates a focus on areas.
  • There is a challenge regarding whether other interpretations, such as ratios of volume or mass, could also be valid, with one participant noting that these would require additional information about the wheels.
  • Another participant posits that one could interpret the question to find the ratio of angles defined by the revolutions of the wheels, highlighting the potential for unintended interpretations.
  • A humorous remark is made questioning if the "ratio of wheels" could simply be considered equal to 1, referencing the number of wheels on the bike.

Areas of Agreement / Disagreement

Participants express disagreement regarding the interpretation of the exam question, with no consensus on what the examiner should do about the differing answers. Multiple competing views remain on the validity of the answers provided by students.

Contextual Notes

The discussion highlights limitations in the clarity of the exam question, as well as the dependence on interpretations of terms like "ratio" and "size." There are unresolved assumptions about what the question intended to ask.

Who May Find This Useful

Readers interested in educational assessment, ambiguity in exam questions, or the interpretation of mathematical concepts may find this discussion relevant.

grzz
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TL;DR
Points of view of examiner and student may not be coincident.
A math exam question asked for the ratio of two wheels given the required information about the number of revolutions made along a certain distance by the two wheels of a penny-farthing bike.

Some students gave the ratio of the radii while others gave the ratio of the areas.

What should an examiner do when confronted with these two types of answers?

Thanks for any help.
 
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Accept them both, since it is the fault of the examiner for writing an ill-defined question!
 
grzz said:
Summary:: Points of view of examiner and student may not be coincident.

revolutions made along a certain distance
... indicates, that the ratio of the circumferences, i.e. of the radii is asked for. Nothing in the text points to areas.
 
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Fresh is right. Would ratios of volume or mass have to be accepted as well?
 
Volume and mass are different; you'd need to know the three-dimensional geometry of the wheel for the former as well as material properties for the latter. Meanwhile, area is a perfectly reasonable measure of 'size' of a two-dimensional region.
 
One can always find interpretations that are not intended if one only is willing to. E.g. one could solve for the ratio of angles, which are defined by all revolutions of the wheels along the given distance.
 
Isn't the "ratio of wheels" equal to 1? One front wheel and one back wheel.
 
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I am inclined to be in favour with the reply of "etotheipi', though I totally missed the perfectly logical reply of 'Vanadium 50'!

Anyway, thanks for all contributions.
 
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