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Rem700PSS

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Please help settle this fractions test question

http://www.ar15.com/forums/topic.html?b=1&f=5&t=991000&page=1

This is what I said:  4 inner / 4 inner + 4 outer + 1 that is neither  = 4/9

This is what others said: 4 inner / 4 inner + 4 outer = 4/8 Pluto  is not a planet.  The test is wrong, the teacher is wrong.

What are the math specialists opinions?

Thank you

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help settle this fractions test question

Hi;

The question is highly ambiguous, since pluto is in the table, I like the answer 4 / 9

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Please help settle this fractions test question

Since it tells you that the planets have been divided into inner and outer, I'd say that Pluto being in neither category means it's not counted as a planet (for the purposes of this question anyway).

It perhaps could have been clearer, but I wouldn't say it was ambiguous.

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Why did the vector cross the road?
It wanted to be normal.

dog-meat

Guest

Re: Please help settle this fractions test question

The only way the problem is consistent is if pluto is not a planet (since if it was pluto would be grouped into either inner or outer categories). Therefore the asterisked note under the table is just clarifying information to tell you that pluto is not a planet and should be ignored (probably for the benefit of those unaware of the recent removal of pluto's planet status). Either the answer is 4/8ths or the problem has contradicting assumptions. Since the latter shouldn't happen in math, the correct answer must be 4/8.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help settle this fractions test question

Hi;

I would, there is no indication that the denominator is just the sum of inner and outer planets. The table provides three categories. In a sense that is the Universal set U = { inner planets, outer planets, neither}. It appears 9 as a reasonable as 8 for the denominator.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

dog-meat

Guest

Re: Please help settle this fractions test question

Hi;

I would, there is no indication that the denominator is just the sum of inner and outer planets. The table provides three categories. In a sense that is the Universal set U = { inner planets, outer planets, neither}. It appears 9 as a reasonable as 8 for the denominator.

Sure there is an indication ... they ask for the fraction of the planets. You can infer from the 2nd sentence and the asterisked note that the set of planets does not include pluto.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help settle this fractions test question

Yep, I stand corrected. Thanks dogmeat and mathsy.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

Re: Please help settle this fractions test question

The only way the problem is consistent is if pluto is not a planet (since if it was pluto would be grouped into either inner or outer categories).

Or, Pluto stands in the middle, right in the limit boundaries of inner planets and outer planets.

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Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away.
May his adventurous soul rest in peace at heaven.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,157

Re: Please help settle this fractions test question

The note about Pluto simply tells us that we should not be considering it in the problem.  So there are 8 planets and the answer is 4/8.  But what a poor question.  As a fractions question the substance of the problem is the easiest one could make it.  But it is wrapped up in a confusing and complex table that makes 'understanding the information' the problem rather than testing the mathematics itself.  The same concept could have been tested with an eight sector pie chart with coloured sectors.  (eg. What fraction are coloured red?)

Advice for teachers:  Think about what you want to test and devise a question that just does that.  Don't make it a comprehension test as well.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob