Four card trickery

[En_Route]

Another old 'un but good 'un.
There are 4 cards with two faces, each one showing a number on one face and a letter on the other.  You can see the upward faces of all 4 cards, showing the symbols: E 6 K 9 respectively. You are asked to test the hypothesis that every card with a vowel on one side has an even number on the other side. Which card or cards should you turn over to test this hypothesis? If you turn over a card which is not relevant to the testing process, you lose the task. May be more fun(!) if those who are interested  give their answers but without any reasoning, so as not to prejudice other attempts.

[The Black Jester]

E and 9.  That's my guess.

[Stevil]

E and 9.  That's my guess.

Agree

[xSilverPhinx]

E, 6, K and 9 (that about covers it )

[En_Route]

E, 6, K and 9 (that about covers it )

I quote " If you turn over a card which is not relevant to the testing process, you lose the task."
I forgot to add that if you lose the task you will be forced to listen to Celine Dion's entire back catalogue at maximum volume until you go insane or deaf, whichever occurs sooner.

[xSilverPhinx]

Okay, okay...

I'd turn over E and 6. I don't know why the two previous posters have said E and 9, would like to find out.

[En_Route]

Too late. My henchmen armed with gargantuan speakers and a tea-chest of vinyl are heading your way,,,

Explanations will follow.

[xSilverPhinx]

Too late. My henchmen armed with gargantuan speakers and a tea-chest of vinyl are heading your way,,,

Explanations will follow.

Excellent, you provide the audio support and I'll provide the stage and ticket-buying people. Party for them, I'll quietly slip out with their money. Send you 33,33%.

[Stevil]

Okay, okay...

I'd turn over E and 6. I don't know why the two previous posters have said E and 9, would like to find out.

What value do you get by flipping the 6?
If it is a consonant, then it doesn't help prove (or disprove) that all vowels have even numbers,
If it is a vowel then it doesn't help prove (or disprove) that all vowels have even numbers.

If however, you flip the 9 then...
If it is a consonant...
If it is a vowel...

[xSilverPhinx]

Okay, okay...

I'd turn over E and 6. I don't know why the two previous posters have said E and 9, would like to find out.

What value do you get by flipping the 6?
If it is a consonant, then it doesn't help prove (or disprove) that all vowels have even numbers,
If it is a vowel then it doesn't help prove (or disprove) that all vowels have even numbers.

If however, you flip the 9 then...
If it is a consonant...
If it is a vowel...

Yes but I still don't see the difference. K isn't a vowel, so it's it doesn't matter if the number is even or not, and 9 is an odd number, so it doesn't matter if the letter is a vowel or not. ???

I wasn't thinking philosophically logically about this question, as in a true or false statement (as in disproving or proving the sentence) but then again my reading comprehension has frustrated me on numerous occasions when I'm tired.

[Stevil]

9 is an odd number, so it doesn't matter if the letter is a vowel or not. ???

Are you sure about that?

[xSilverPhinx]

Derp, I see it now. If it was a vowel it would prove the statement to be false.