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Is it just me or is this an odd way to word this math problem

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Well? (MULTIPLE CHOICE!)

  • Question was stupid

  • Bubbleawsome was stupid

  • I couldn't tell you, I'm bad at math


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You are giving them WAY too much credit

It wasn't designed to be tricky like that, it was simply a screw-up

you can see from the original test this was pulled from they weren't trying to be tricky, they just suck at word problems
https://www.google.com/url?sa=t&rct...01.pdf&usg=AFQjCNE-gs0wbhkQHvqHjwW1qDtWuP9u0w

Why wasn't it designed to be that way? This is the exact type of question that appears on the GRE every session. "Given that" is a very common phrase in these word problems and has only one specific meaning when it is used this way.
 
The original question does not tell us that the item chosen contained chocolate (or was a man). It asked to chose at random out of all desserts.
Yes, it asked to choose at random out of all deserts. We get that part. Then you are missing the last part of the question. From the OP: "given that it contains chocolate" from the OP's second posting of the question "given that is contains chocolate". We now have additional information. We know that it isn't plain. Thus, we can't consider it being plain.

I told you the randomly chosen person was a man. Now with that additional information, what is the chance that the person chosen has nuts?

You are correct without that additional information. But now that we have that additional information, you are no longer correct. A randomly chosen person from that specific room has a 75% chance of having nuts. But a randomly chosen person who we now know is male has a 100% chance of having nuts.
 
Why is their not a possibility of choosing a non-nutted non-chocolate desert?

because you are told that it contains chocolate

which means that there is 100% chance it contains chocolate and a 0% chance that it doesn't contain chocolate

just like if you select a left-handed person, there is a 100% chance they are left-handed
 
Why wasn't it designed to be that way? This is the exact type of question that appears on the GRE every session. "Given that" is a very common phrase in these word problems and has only one specific meaning when it is used this way.

because it's a basic high-school stats course, not a logic course

granted those aren't completely unrelated, but here they're testing basic statistical knowledge

and you can look at some of the other problems (specifically #8) that are just completely nonsensical

my guess is the person who created the questions wasn't a native english speaker
 
Yes, it asked to choose at random out of all deserts. We get that part. Then you are missing the last part of the question. From the OP: "given that it contains chocolate" from the OP's second posting of the question "given that is contains chocolate". We now have additional information. We know that it isn't plain. Thus, we can't consider it being plain.


That is why I split the question. The first part asks that we randomly choose one of all the possibilities. Anyone disagree?

Then, if the the result of that choice is chocolate (86% probability, that the result was actually chocolate does not change that probability to 100%) it asks what the probability that the 86% chance also included the 30% chance of nuts.
 
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because it's a basic high-school stats course, not a logic course

granted those aren't completely unrelated, but here they're testing basic statistical knowledge

and you can look at some of the other problems (specifically #8) that are just completely nonsensical

my guess is the person who created the questions wasn't a native english speaker

I see that he further edited the OP at the top.

SO, the answer that he posted is the supposed correct answer, even though the wording is as we understand it--chocolate should not be included?

As worded, I don't think that question is uncommon for any type of high school class--Critical thinking should be tested at any age.
 
That is why I split the question. The first part asks that we randomly choose one of all the possibilities. Anyone disagree?

yes

you can't split the question, it's one question with conditions

the condition is that the choice is chocolate, so the 86% is irrelevant. it is now 100%

we start knowing that there is 100% chance it is chocolate
 
That is why I split the question. The first part asks that we randomly choose one of all the possibilities. Anyone disagree?

Then, if the the result of that choice is chocolate (86% probability, that the result was actually chocolate does not change that probability to 100%) it asks what the probability that the 86% chance also included the 30% chance of nuts.

right, that's what I thought at first. But again, that's the problem. "Given that it contains chocolate" is just as important as "random sweets." You can't discard the final part of the problem because you think the first part is more important (implied parenthesis!)

As worded, it is only asking for the % of candies with nuts in a random selection of chocolate candies.
 
As worded, I don't think that question is uncommon for any type of high school class--Critical thinking should be tested at any age.

if the answer they were looking for was 30%, then i would agree that it was intentional and a logic problem

but the answer they were looking for was 34.9%, which means they simply screwed up the question
 
right, that's what I thought at first. But again, that's the problem. "Given that it contains chocolate" is just as important as "random sweets." You can't discard the final part of the problem because you think the first part is more important (implied parenthesis!)

As worded, it is only asking for the % of candies with nuts in a random selection of chocolate candies.

I thought one of the main ideas of statistics is that the results of a single test do not change the probability.

I don't see that I am discarding anything. Others are discarding the possibility of plain because the result of chocolate was given to us.
 
if the answer they were looking for was 30%, then i would agree that it was intentional and a logic problem

but the answer they were looking for was 34.9%, which means they simply screwed up the question

Yes, this seems to be the case.

I am simply saying that the question as worded is not unusual at any level--it is quite common.

But until the OP updated with the actual answer, it was not obvious to me yesterday that it really was worded improperly. (I didn't notice his updates until ~now, so my previous posts today reflect that, fwiw)
 
I thought one of the main ideas of statistics is that the results of a single test do not change the probability.
This isn't a single test.

You are thinking "randomly choose a treat". To see why this interpretation is wrong, your randomly chosen treat could possibly be plain. But the problem said there was no possibility of it being plain, it was chocolate. Thus, this isn't a simple random choice.

The question actually asks "randomly choose a treat and keep randomly choosing it until it is chocolate".
 
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I thought one of the main ideas of statistics is that the results of a single test do not change the probability.

I don't see that I am discarding anything. Others are discarding the possibility of plain because the result of chocolate was given to us.

Others are discarding the possibility of plain because it is not possible.

As worded, only chocolate is possible, so the question--as worded--only asks for the % of nuts in chocolate candies, only. It is a common word problem.

However, it is clear that the test writers were trying to create the problem as you see it. They erred in writing the problem.

It is also common to see errors like this, even in major, multi-print textbooks. As one tiny example, I had to point one out to my professor in general chemistry one year.
 
This isn't a single test.

You are thinking "randomly choose a treat".

The question actually asks "randomly choose a treat and keep randomly choosing it until it is chocolate".

It does?

"Find the probability that a dessert chosen at random contains nuts given that is contains chocolate."

1. Choose a desert at random.
2. Does it contain chocolate? (luckily, it does!)
3. What is the probability that it has nuts?
 
It does?

"Find the probability that a dessert chosen at random contains nuts given that is contains chocolate."

1. Choose a desert at random.
2. Does it contain chocolate? (luckily, it does!)
3. What is the probability that it has nuts?

What if you were unlucky and it doesn't contain chocolate? You just violated the problem. Thus your view of the problem is not allowed.

If it were allowed to be plain, then you are correct. But that was strictly forbidden in this wording.
 
Seems to me this is a lesson in psychology. It doesn't matter what the words actually mean; you have to recognize each course's buzzwords and jargon and then give them the answer they want, not the answer they asked for. It's actually great practice for the workplace.
 
What if you were unlucky and it doesn't contain chocolate? You just violated the problem. Thus your view of the problem is not allowed.

There is a 14% probability that the randomly chosen item doesn't contain chocolate. What specific part of the problem does that violate?

The question never wavers from discussing one item chosen at random from the total number of items.
 
There is a 14% probability that the randomly chosen item doesn't contain chocolate. What specific part of the problem does that violate?

The question never wavers from discussing one item chosen at random from the total number of items.

Except, it does.
 
those who think that if a dessert is chocolate, there is a 100% chance it is chocolate: drinkmorejava, zinfamous, Bubbleawsome, tynopik, Paladin3, Brian Stirling, DaveSimmons, fralexandr, dighn, jchu14, TallBill, ElFenix, gorcorps, DigDog

those who think that if a dessert is chocolate, there is only an 86% chance it is chocolate: Humpy

what I'm saying is that this has been explained many times in many ways, so rather than continuing to insist you are right, accept that you are wrong and try to figure out why
 
those who think that if a dessert is chocolate, there is a 100% chance it is chocolate: drinkmorejava, zinfamous, Bubbleawsome, tynopik, Paladin3, Brian Stirling, DaveSimmons, fralexandr, dighn, jchu14, TallBill, ElFenix, gorcorps, DigDog

those who think that if a dessert is chocolate, there is only an 86% chance it is chocolate: Humpy

what I'm saying is that this has been explained many times in many ways, so rather than continuing to insist you are right, accept that you are wrong and try to figure out why

I'd like to know if the popular answer was one of the options on the test (wtf is the popular answer? Did you guys figure that out yet?). Then you can argue that not only was the question wrong, the answers were wrong too. 🙂

And, holy shit! They tell us at the onset that there is an 86% chance it is chocolate. What are you even saying?
 
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