## Die and pi

Posted on: March 31st, 2014 by
3

Estimate the value of pi using a 6 sided die. - via Goldman Sachs interview, reposted in CSE blog

## Car wheels

Posted on: March 30th, 2014 by
2

A car has 4 tires and 1 spare tire. Each tire can travel a maximum distance of 20000 miles before wearing off. What is the maximum distance the car can travel before you are forced to buy a new tire? You are allowed to change tires (using the spare tire) unlimited number of times. - via Gpuzzles

## Covering

Posted on: March 25th, 2014 by
What is the largest square table that you can cover completely using 3 square napkins of side 1 unit? You cannot tear the napkins, but you can fold them or overlap them, and the napkins are allowed to drape over the side of the table. - via Mind your decisions.

## Form a triangle

Posted on: March 23rd, 2014 by
1

You certainly can make a triangle from 3 unit toothpicks called a, b and c (each being a side opposite angles A, B, and C respectively. But what if you were to: Cut a piece from b and burn it. Cut a piece from c and burn it. Leave a alone. What are the probabilities that you will be able to form the following (using the entire Continue reading the story "Form a triangle"

## Hat puzzle

Posted on: March 20th, 2014 by
2

There are 3 people each wearing either a white or a black hat. They can see everyone's hat except their own. They must design a strategy so that they can maximize the chances of success of at least one person guessing the hat color correctly and no one guessing wrong. They cannot talk to each other after the hats have been placed on their heads. Continue reading the story "Hat puzzle"

## Pairing

Posted on: March 18th, 2014 by
1

You want to pair 2n students into n pairs of 2 students each. You like to do it on consecutive days so that no two students are paired together twice. What is the maximum number of consecutive days for which you can achieve such a pairing?

## jumping coins

Posted on: March 16th, 2014 by
There are n coins placed in a row. The goal is to form n/2 pairs of them by a sequence of moves. On the first move a single coin has to jump over one coin adjacent to it, on the second move a single coin has to jump over two adjacent coins, on the third move a single coin has to jump over three adjacent coins, and so on, Continue reading the story "jumping coins"

## What does this equation mean?

Posted on: March 14th, 2014 by
2

$(\sqrt{-1})(2^3)(\sum\pi)$ - via Gpuzzles

## Guess hat color

Posted on: March 14th, 2014 by
1

Consider the picture below: In this picture, there are 4 prisoners buried in the ground. There is a brick wall separating A and B. C can see B and D can see both B and C. Between the 4 prisoners, 2 white and 2 black hats are worn. No one can see their own hat color. The hat color is fixed Continue reading the story "Guess hat color"

## Rational k-th power

Posted on: March 12th, 2014 by
1

For any k, the number A[k] is formed by writing all the perfect k-th powers in order after the decimal point. For example A[1]=0.1234567891011121314.... and A[2]=0.149162536496481100121144.... Is there a value of k for which A[k] is a rational number? - via AMS math society

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