Insight-The third eye
Volume XI

INTERESTING LINKS

Puzzles

Berkeley Puzzle Page

Turkish Intelligence Portal

The Archimedes Lab

Mathematics

IMO problems

The Putnam archive

Blogs

Timothy Gowers' blog

Terence Tao's blog

 

 



Questech - Top 10 puzzles

Anup Rao

In this special edition of Questech, we bring you the best puzzles from our extensive archives. Solutions in two days.

1. Put on Your Thinking Hats!
Three men on a safari are captured by cannibals (clichéd, eh?). The men are given one chance to escape with their lives (yawn). The men are lined up such that the last man in the line can see the backs of the other two, the middle man can see
the back of the front man, and the front man can’t see anybody (had a feeling you would be familiar with the concept).

Anyway, the men are shown five hats, three of which are black and two are white. The men are then blindfolded, and one hat is placed on each man’s head. The remaining two hats are hidden away. The blindfolds are removed. The men are told that if just one of the men can guess what hat he’s wearing, they may all go free. (These cannibals sure have time on their hands!).

Time passes. Finally, the front man, who can’t see anyone, correctly guesses the color of his hat. What color was it, and how did he guess correctly?

2. Contem-plate!
My brother and I play a game in which we take turns placing plates on a clean table. All the plates must be the same size, lie flat on the table, and no plate may overlap another. The first person who is unable to place another plate on the table without it falling off or moving another place must wash the dishes for the next week. The table is a perfect circle, with a five feet diameter. Each plate is also a perfect circle with a ten inch diameter. If I am given the choice of going first or second, which do I choose, and what will my strategy be?

3. Prime Suspects
In the following multiplication sum, all the figures have been replaced with asterisks. Given that each figure is a prime number (2, 3, 5 or 7), can you reconstruct the problem and find the answer?

Puzzles 4 - 7

PREVIOUS PROBLEMS

In this section, you can browse through the problems that have appeared in previous issues of InsIghT, get hints and see the solutions.

Issue 11.2

Issue 11.1