@fairfax - Yes that is a good point, I didn't consider that. I guess in my initial answer I was too open minded about the meaning and I had assumed it worked both ways. Limiting it down to the one way statement that then yes, E 4 would work.

@Minty, if I were to say all cashew are nuts, does that mean all nuts are cashews? It isn't math, but set theory. It has nothing to do with the equals sign but with set inclusion. Wait till you are farther along in high school and have taken set theory and you will understand.

The question does state there are "four cards in front of you". I suppose hypothetically you could grab a blank card and a pen from some where and write what ever you want on the front and back of the cards, making it impossible to declare any rule about the cards. But none of this is mentioned in the question.

Regarding your question, "what's the difference between and odd vowel, and a vowel odd." Are you referring to this point you raise in your earlier post:

> You decide to turn over the rest of the cards just for arguments sake and they end > up being

> E1
> C6
> 5
> 4B

>The statement is no longer true, While A confirms the statement, C and 4 Are irrelevant, 5 now proves it wrong.

In that situation we can see that the proposition was indeed true. The fact 5 has a consonant on the other side does not invalidate the proposition.

"If a card has a vowel on one side, then it has an odd number on the other side."

For the proposition is NOT "... And if there is an odd number on one side there is a vowel on the other".

@spy - Yes okay, I understand now. ''For the proposition is NOT "... And if there is an odd number on one side there is a vowel on the other".''

That makes sense.

@Draug- I have finished the British equivalent of high school already, I am currently doing my undergrad at University. Although I never did ''Set theory'' I wish I did, the concept fascinates me.

How about another little puzzle?

You are given 10 coins and told to arrange the coins on a flat surface such that they form 5 different lines of 4 coins each. The 5 lines may intersect but may not overlap, i.e. a line of 5 coins is not 2 lines of 4 coins. Go.

@Minty - Really? I thought everyone who had gone onto college (at least in my era) took Probability and Statistics, Calculus (or pre-Calc at least), Circular Functions, and Set Theory.

Do the lines have to be straight, or can I turn them?

Also this would be so much easier if I wasn't a poor student with an empty wallet, so I could actually try this out instead of drawing on a note pad.

It takes 7 coins to get two lines (with intersect but no overlap) and 9 coins to get three (intersect with both existing lines), how you can get two more lines with just one more coin, I don't have a clue.

Lines are straight, you're not putting coins on a spherical surface. You're putting them on a plane.

o
o o o o
o o
o o o o
o

@draug - I Covered all of that except Set Theory.
Though this year at university I have a maths and statistics module for my accounting course. And we may have covered Set theory at some point without me realising it :P, there is one part of the module that I'm failing, but overall scoring around 70% far above the 40% required to Pass the module. Thankfully I can do Calculus which makes up a large chunk of the module.

MeepMeep, that's 12 coins.

Grrrr...Let's try again

___o___
o_o_o_o
_o___o_
o_o_o_o
___o___

Opps, lemme think...how to trim the fat. LoL.

From another thread where it went despite my reading thisone at the time...

Draugnar (158 )
11:23 AM

WAIT! I got it! A 5 pointed star uses ten intersections and has 4 intersections each!

Note the time, it was 3 minutes before Meep's drawing so that didn't give me any clues.

Too bad Meep has me muted.

Draug got it, it's a pentagram.

Someone want to copy/paste my answer to show Meep it was already solved?

@draug, what are you calling circular functions? I've taken more math than most people have, and I don't recognise that term.

It's a form of Trigonometry.

From http://www.cliffsnotes.com/study_guide/Circular-Functions.topicArticleId-11658,articleId-11591.html

Circular functions are defined such that their domains are sets of numbers that correspond to the measures (in radian units) of the angles of analogous trigonometric functions. The ranges of these circular functions, like their analogous trigonometric functions, are sets of real numbers. These functions are called circular functions because radian measures of angles are determined by the lengths of arcs of circles. In particular, trigonometric functions defined using the unit circle lead directly to these circular functions.

Ah, circle trig we called it. Ok thanks.