April 2, 2009

Probability Riddles



Two Persons A and B. Person A picks a random number from 1 to 1000.
Then person B picks a random number from 1 to 1000. What is the
probability of B getting number greater then what A has picked?

3 comments:

  1. There are a million possible combinations of picks (1000*1000). Exactly 1000 of these are matching pairs. Of the rest (999,000), exactly half the time B's pick will be greater than A's.

    Half 999,000 is 499,500 which is 49.95% of 1,000,000.

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  2. Secret Squirrel, you are correct. By mistake I worked out the solution for numbers between 1 and 10, in which case the answer is 45%.

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