perplexus.info :: Logic : Formal Reasoning

Formal Reasoning (Posted on 2004-12-15)

I present to you a deck of 4 cards. Each card has on one side a letter of the alphabet, and on the other side a single digit from 0-9.

I propose a hypothesis that may apply to this deck:
If the letter is 'E', then the number on the other side is '4'.

I then drop the 4 cards on the table, and you see: 'B', '7', 'E', '4' (on the respective cards).

Which of the 4 cards must you turn over to verify or disprove my hypothesis?

Submitted by SilverKnight

Rating: 3.0000 (22 votes)

Solution: (Hide)

You must turn over the '7' and the 'E'.
If the other side of the '7' is an 'E', you will disprove the hypothesis. If the other side of the 'E' is not a '4', then you disprove the hypothesis.
The values on the other two cards will have no bearing on the hypothesis.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
answer	K Sengupta	2008-02-21 14:28:34
my thoughts	brad	2005-03-29 21:07:48
More thoughts on my previous answer	NetGoofy	2005-03-23 19:13:20
How about this.	NetGoofy	2005-03-23 19:05:04
Maybe?	Kardo	2005-03-23 06:11:47
Turn the E and 7	jim jones	2005-03-15 10:48:53
Turn the E and 7	jim jones	2005-03-15 10:48:53
No Subject	Ujjawal	2005-03-11 13:16:04
solution	Jeff	2005-03-09 04:04:09
re(5): Solution	Dustin	2005-03-07 01:20:18
re(4): Solution	Sean	2005-03-07 00:37:42
re(3): Solution	Dustin	2005-03-06 23:14:23
re(2): Solution	Sean	2005-03-06 23:08:48
re: Solution	artemis	2005-03-06 15:33:10
Solution	Sean	2005-03-06 08:47:21
Solution	artemis	2005-03-05 17:00:38
The REAL Solution	NetGoofy	2005-03-01 17:45:33
solution	aq	2005-02-28 20:53:46
Possible Solution	Robyn	2005-02-23 17:49:35
solution	james	2005-02-22 01:48:53
solution.	Pete	2005-02-10 23:30:04
CORRECTION!!!	dev e.	2005-02-07 02:29:12
weird...	dev e.	2005-02-07 02:01:08
the solution	durrell	2005-02-05 16:42:17
solution	juan m. perez	2005-02-04 22:20:48
the answer	derek	2005-01-19 23:46:10
re: answer	jeff	2005-01-19 07:41:27
answer	jeff	2005-01-19 07:40:08
answer	Cassandra	2005-01-02 01:21:05
answer	jenni	2004-12-27 23:16:56
ANSWER	SIMONE FOLK	2004-12-24 19:44:14
answer???	sarah	2004-12-22 05:33:11
I think this is it	mick	2004-12-19 03:58:29
re: The Answer	gregory	2004-12-19 01:13:19
The Answer	Chris, Phd	2004-12-19 00:32:11
Correcrt Solution	debajit	2004-12-18 09:39:12
solution	daniel	2004-12-17 23:27:10
Tis the Reason	RandyOrton	2004-12-17 14:38:59
Solution	Richard Carr	2004-12-17 13:46:38
possible solution	tawnya	2004-12-17 06:07:06
re: I don't understand	Penny	2004-12-17 02:13:45
I don't understand	Dainma Felpry	2004-12-17 00:11:13
Solution by counterexample	e.g.	2004-12-16 10:52:25
re: solution-and i did not steal it, promise	Nosher	2004-12-16 02:34:07
solution-and i did not steal it, promise	Linda	2004-12-15 20:31:25
Solution	Eric	2004-12-15 17:23:06
Good problem	SteveH	2004-12-15 17:18:28
re: Solution	Federico Kereki	2004-12-15 17:08:10
solution	bob909	2004-12-15 16:46:32
Solution	Joshua	2004-12-15 16:24:32
re: Layman's Logic	Penny	2004-12-15 16:09:03
Layman's Logic	Juggler	2004-12-15 15:50:28
re: 3 Scenarios	Timothy Bard	2004-12-15 15:42:24
re: Solution	Penny	2004-12-15 15:40:00
re: Is there a catch ?	Federico Kereki	2004-12-15 15:23:50
Solution	Penny	2004-12-15 15:14:04
re: 3 Scenarios	nikki	2004-12-15 13:58:47
3 Scenarios	Syzygy	2004-12-15 13:23:56
Is there a catch ?	Syzygy	2004-12-15 13:16:50
Solution	Old Original Oskar!	2004-12-15 12:59:10

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