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# Iccle question pour vous (with prize) watch

1. There are 4 cards

R, G, 2, 7

each card has a number on one side + a letter on the other

rule: all 'R's have '2' on the other side.

which cards would you need to turn over to prove the rule?

PM your answers to me + the 1st will get some rep.

my profile (to pm me)

lou xxx
2. I've sent you a pm
3. (Original post by theone)
I've sent you a pm
and you got it right! *is far too kind to name and shame those who got it wrong*

you want to explain it... or we could let people put what they think on here for a bit...

lou xxx
4. (Original post by lou p lou)
and you got it right! *is far too kind to name and shame those who got it wrong*

you want to explain it... or we could let people put what they think on here for a bit...

lou xxx
best to leave it for a while
5. here is the right answer...

(Original post by theone)
Here's what I think:

You have to turn over the R and the 7.

If the 2 is turned over and there isn't an R, this doesn't mean anything since our hypothesis is that all R's have 2 on the other side, this doesn't imply all 2s have R on the other side.

Similarly with the G.

If you turn over the 7 and get an R, this disproves the rule, similarly if you turn the R and don't get a 2. So to be certain you have to turn both the 7 and the R.
a group of psychologists (wason et al) tested students with this and only 5-10% got it right, they repeated it a few years later and 12% got it correct. I was the only one in the class who got it, but i think you either it straight away or not at all (unless it's explained).

lou xxx

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