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Johan Linde
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I am in the process of reading 'The Tipping Point' and was not comfortable with the brain teasers on pages 159 and 160. If one follows the instructions literally, you end up with four separate cards labeled 'A', 'D', '3' and '6', obviously on the front, and with nothing on the back of the cards. There has been no instruction to write numbers on the back of the cards. The rule however states that a card with a vowel should have an even number on the other side. Does that now mean that one should write an even number on the back of the card with a vowel, which is card A? Must one then assume that it should be the number 6 on the back of card A, or might it be any other even number? And then, should one write numbers on the back of cards 'D', '3' and '6' as well, or should one write letters on the back of cards '3' and '6', following the rule about vowels and uneven numbers? If you write letters on the back of cards '3' and '6', should those letters be 'A' and 'D', or could they be any letters, as long as the letter on the back of card '6' is a vowel? So let us assume that one ends up with four cards labeled front and back as follows: A/6, D/3, 3/D and 6/A. One only has to check the 'A' card as that is the only card with a vowel visible on the front. The rule does not require an even numbered card to have a vowel on the other side, or for that matter, an uneven numbered card to have a consonant on the back of it. Another valid scenario might be A/ , B/ , 3/ and 6/ . As there were no instructions to write numbers or letter on the back of the cards. Turning card 'A' would be sufficient to confirm that the rule was not adhered to. It just gets more and more confusing, and I believe the brain teaser does not work because the instructions are not specific enough. The same goes for the next brain teaser where "four people are drinking in a bar. One is drinking coke. One is 16. One is drinking beer and one is 25. Given the rule that no one under 21 is allowed to drink beer, which of those people's ID's do we have to check to make sure the law is being observed." The correct answer is given as: 'The beer drinker and the 16 year old". Once again the instructions are not specific enough and many different scenarios might be valid under the rules as stated. For example we know that four people are drinking. We know that one of them is drinking beer, and one is drinking coke. That leaves two drinkers and we do not know what they are drinking. Let us assume that the two unspecified drinkers are also drinking coke. That would mean that we only need to check the ID of the beer drinker, unless if he/she is the person we know to be 25, which means that we do not need to check his/her ID, or anybody else's, as the others are all drinking coke in this valid scenario. The brain teaser fails again due to a lack of specificity.
Commented Jan 21, 2010 on More Gladwell Brainteasers at The Faculty Lounge
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Jan 20, 2010