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Monday, 24 November 2014

Cards inside envelopes

Here is a combinatorics related puzzle.
We have 6 envelopes numbered from 1 to 6.  Likewise we have 6 cards numbered 1 to 6.
You have to put each card in one envelope(it would have only 1 card), such that the card number is never the same as the number of the envelope its placed in.

Question 1: How many different ways can it be done in?

Question: If card # 1 is to be always placed in envelope #2, other constraints remaining same, how many ways are possible now?

Will post my solution in some days.

Saturday, 15 November 2014

Solution to the puzzle of Same number of coin tosses

Here is my solution to the probability puzzle asked last week about finding the probability of 2 people tossing a fair coin 6 times independently, and coming up with same number of heads or (tails)
I had written it on a paper, so decided to put a image snapshot of that solution. Hope its readable.
(Whats the probability of that:-) )

Saturday, 8 November 2014

Same coin tosses

Here is a nice puzzle about Probability theory.

If two people toss 6 fair coins independently at same time, what is the probability that they have same number of tails come up.

I will post the solution in a while.