Dazed Birth Days

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Dazed Birth Days

At this point one of the students raises his hand and goes: "I'll bet you that at least two of us here have the same birthday."

By Mukul Sharma

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Published: Thu 14 Jan 2016, 11:00 PM

Last updated: Fri 15 Jan 2016, 11:05 AM

E4
It is well known that in any group of at least 23 people, the odds are greater than 50 per cent that at least two of them would have the same birthday. There was this professor teaching elementary probability theory to an undergrad math class when he tells them that with 30 people instead of 23, the odds would become much higher. "But," he says, "since there are only 19 students in this class, the odds are much less than 50 per cent that any two of you have the same birthday."
At this point one of the students raises his hand and goes: "I'll bet you that at least two of us here have the same birthday." To which the professor replies: "It wouldn't be right for me to take the bet because the probability would be highly in my favour." "I don't care," says the student, "I'll bet you anyhow."
"Okay doke," says the prof and promptly proceeds to call on the students one by one to announce their birthdays until, about halfway through, both the students and the professor look at each other and both slowly realise
he shouldn't have taken the bet. Why not? (Incidentally, the student making the bet didn't know anyone else's birth date.)

DEAR MS

(The puzzle was about two people alternately painting the faces of a cube and the winner being the person who painted last. The question was who would win? - MS)
Ahead-Of-The-Game-Dept:
The second player can always win the game. He can do so by colouring the face opposite to that coloured by the first player with the same colour. As there will be six turns totally if this rule is followed, the second player will automatically win.
  • Dhruv Narayan,
dhruv510@gmail.com
(The other question was why a cork floating in the middle of a half full glass of water migrates to the edge
but stays in the centre when the water is filled right up to the brim. - MS)
Mass-Communication-Dept:
The basic principle is any two bodies in the universe attract each other depending upon their mass, the distance between them, the gravitational pull and, of course, other factors such as friction, which also
play a role. When the cork is in the middle, the G-pull of the wall of the tumbler eventually attracts the cork and it stays stuck to it. When the tumbler is completely full, there is essentially no wall surrounding the cork to pull towards it, so it floats in the middle. I am a surgeon, not a physicist, but I suppose this is the explanation.
(The third problem was: "The letters forming COLD can each be shifted forward three positions in the alphabet to form FROG. Similarly BALK can be turned into ONYX by shifting them 13 positions ahead. How rapidly can you work backwards from the following 10 words." - MS)
Shifty-Letters-Dept:
The answers for the question related to finding the original words: (1) ADDER; (2) CHAIN; (3) FILLS; (4) MILLS; (5) COBRA; (6) BANJO; (7) CHEER; (8) SNEER; (9) SHEER; (10) PECAN.
  • Aaditya Shankar Natarajan,
BEEFS started out as ADDER, INGOT came from CHAIN, LORRY from FILLS, SORRY from MILLS, FREUD from COBRA, FERNS from BANJO, JOLLY from CHEER, TOFFS from SNEER, TIFFS from SHEER and TIGER originated from PECAN.
  • Ramesh Mahalingam,
ramesh@idealmc.com
(Yes, Joel John, joeljo2104@gmail.com and Vinod Mahajan, vm1966@gmail.com - you also got it right in time. - MS)

ENDGAME(S)

  1. You have four straight pieces of fencing: 1, 2, 3, and 4 metres in length. What's the maximum area you can enclose by connecting the pieces if the land is flat?
  2. Here's an encrypted message: "G T Y O R J O T E O U I A B G T". Can you get what it is?
(To get in touch with Mukul, mail him at mukul.mindsport@gmail.com)


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