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Monthly Archives for September, 2013

Find the next sequence

Posted on: September 11th, 2013 by

5, 25, 325, 4325, ? via Dan Hersham

Coloring planes

Posted on: September 10th, 2013 by

Every point in the plane is colored either red or blue. For a given distance d, show that there always exist 2 points that are distance d apart whose end-points have the same color. via cut the knot


Posted on: September 9th, 2013 by

A town has n people and m clubs. Each club has an odd number of people. Each set of 2 clubs has an even number of common members (can be 0 too). Show that m cannot be greater than n. via Math Exchange

A game of probabilities

Posted on: September 8th, 2013 by

A standard deck of 52 playing cards is shuffled. Then the cards are dealt one at a time from the top of the deck until an ace occurs. Then the next card is handed over to you. What are you more likely to obtain? The ace of spades or the two of hearts? - via Math Exchange

Look at each other

Posted on: September 7th, 2013 by

A group of n people are asked to stand against the wall. Each person chooses a location uniformly at random on the wall and independent of the other people. Then each person is asked to look at his nearest neighbor from the group. What is the expected fraction of people (as a function of n) who are looking at each other? via Math Exchange

Reflecting beads

Posted on: September 6th, 2013 by
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Four identical beads are at the corner of a square on a flat table of infinite dimensions (a plane). Any bead can move by reflecting itself with respect to any other bead, i.e. A bead can move from position x to position y if there is a bead at position (x+y)/2. Is there a sequence of moves that can reposition the four beads to the Continue reading the story "Reflecting beads"

Removing apples

Posted on: September 5th, 2013 by
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Alice and Bob take turns to remove apples. Alice must remove at least a0 apples and no more than a1 apples in his turn unless there are less than a0 apples in which case Alice removes all the remaining apples. Bob must remove at least b0 apples and no more than b1 apples unless there are less than b0 apples in which case Bob removes Continue reading the story "Removing apples"

How much is Jennifer?

Posted on: September 4th, 2013 by

Susan=10 Arabella=20 Jim=5 Neil=5 Richard=10 Jennifer=? SPOILER WARNING ... ... ... ... ... via youtube

A geometry puzzle

Posted on: September 3rd, 2013 by
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Let ABCD be a square of side 1 unit. Let E,F,G,H be the mid-points of AB,BC,CD,DA respectively. The lines FA, AG, GB, BH, HC, CE, ED and DF enclose a regular octagon of side s. Express s^2 as a rational number. via Quora. SPOILER WARNING ... ... ... ... Solution can be found here

Five with zeros

Posted on: September 2nd, 2013 by

How will you obtain 5 using 5 zeros?

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