Braingle: 'Farm Dog' Brain Teaser

Farm Dog

Trick brain teasers appear difficult at first, but they have a trick that makes them really easy.

Puzzle ID:	#25004
Fun:	(2.04)
Difficulty:	(2.87)
Category:	Trick
Submitted By:	cnmne

The numbers 2 and 5 are the only two prime numbers that end in 2 or 5. What is the rationale for the following groups of numbers?

3 17 31 47 61
7 19 37 49 67
11 23 41 53 71
13 29 43 59 73

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Comments

deepsea Aug 01, 2005	the title gave it away
SaturnCat08 Aug 01, 2005	Good One!
SaturnCat08 Aug 01, 2005	Good One!
SaturnCat08 Aug 01, 2005	Good One!
gorillazgirl Aug 01, 2005	cool
froggygg Aug 02, 2005	Good teaser!
lisha_kc Aug 03, 2005	how did the title give it away???? And was the 2 and 5 thing suppose to throw me off??? aw well...good one!
cnmne Aug 03, 2005	The 2 and 5 comment was meant to be misdirecting, hence Trick being the category. Additionally, 49 is not a prime number, again meant to be misdirecting. As for the title, it points to the children's song, where a farmer had a dog named Bingo.
thecowancannons Aug 04, 2005	not bad
Riddlerman Aug 08, 2005	ratio-what?
turtlesrock44 Aug 22, 2005	????????????????
swithie Sep 05, 2005	My head hurts
amelia639 Sep 16, 2005	i couldn't get it because i don't now what rationale means
bhssoccer23 Sep 20, 2005	rationale means reason i would have gotten it if i knew my bingo numbers!
JessicaG Oct 12, 2005	a goodish teaser, but impossible if you don't know bingo numbers
shenqiang Oct 19, 2005	What's a bingo number?
rkaaland Dec 09, 2005	I got it!!! Only after I looked at the answer Good job!
lukeschett Jan 25, 2007	Great.
reptile5000 Jun 15, 2007	should be in another category, i think
annvie9 Mar 31, 2008	got me there! (I post that to a lot of teasers )
Calehay Oct 31, 2008	Oh, I got it! I haven't played Bingo in ages and forgot all the rules, but I got it somehow. For those that were wondering, Bingo is a game. http://en.wikipedia.org/wiki/Bingo_(U.S.) The title refers to the children's song: "There was a farmer and a dog, and Bingo was his name-O; B-I-N-G-O, B-I-N-G-O, B-I-N-G-O, and Bingo was his name-O." However, "a farmer" is sometimes replaced with " a man who" so there's the stem of the confusion.
coolkcoolk Oct 27, 2009	great one! had no idea