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Random Primes (Posted on 2003-07-10) Difficulty: 4 of 5
If you pick any two integers at random, what is that probability that they will be relatively prime? ("relatively prime" means that the two numbers share no divisors except 1)

Tell how you end up with the answer.

See The Solution Submitted by not_so_einstein    
Rating: 4.0000 (2 votes)

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re(2): First steps.... | Comment 4 of 9 |
(In reply to re: First steps.... by friedlinguini)

Rather than
1 - (1 - 1/4) x (1 - 1/9) x (1 - 1/25) ... (1 - 1/nē)... for all prime n,

the subtracting of probability of non-rel-prime from 1 has already been done within each parentheses to give rel-prime (for the particular prime) so the final product is the answer without subtraction from 1.

  Posted by Charlie on 2003-07-10 08:30:26

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