FACT: Each card has a number on one side and a letter on the other.
HYPOTHESIS: Every card that has a vowel on one side has an even number on its opposite side.
THE TEST: Which card or cards must you turn over in order to test the Hypothesis?
Type your answer in the Reply field below and Save.
The 15 possible answers are:
All four cards: A B C D
Three cards: A B C / A B D / A C D / B C D
Just two cards: A and B / A and C / A and D / B and C / B and D / C and D
Just one card: Card A only / Card B only / Card C only / Card D only
612119d
bluntwriting88
capched
cardinal7218
cfriery
chavanillo
Chris McGee
christianity19
clementine102
comicdub
compiistudent
corinnebuck1219
daphneblake25
dayzur
g903254
gabythefujoshi18
goldin92
gooferious
hailthegreat8
hazelnutlatte123
honeysucklelilac
icedcoffeeislife
imgoingswimming
iwantpopsicle
doorknob9
BabyGoat
jeffbezos123
jets1313
johnwick66
justheretopass
kobebryant32
kowiklinski
l8tersk8ter
aquarela
metro111c
mrmba1
mysterylimbo
nina525
nousernamefound1
nyaj32
oaktree1234
pardonmyfrench13
person345
pomegranate4800
Jessicariccio
rosekyd
rowanrat
rowanstudent24
runnerd4
shadowswife
SmilingDogTheProfWants
sonnypetro29
tcarter101
thecommoncase
wafflesrgud22
wazoo1234
yourfavoriteanon
Counterintuitivity 
A and C
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I take that back, all four cards
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Want to try again? 🙂
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Just two cards: A and C
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you will need to flip 2 cards. B and C. B needs to be an even number when flipped and C needs to be a vowel when flipped in order to prove the hypothesis.
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A and C
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It just cards A and C
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Card C, Card A, Card D, Card B
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Just A and C
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All Four
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just A and C
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Cards B and C
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you will need to flip 2 cards. A and C. A needs to be an even number when flipped and C needs to be a vowel when flipped in order to prove the hypothesis.
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A and C
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a and c
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All of the cards
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Huh. Nobody said A and D.
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Card A and Card D
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(E and 3)
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