Which is mathematically more random?

Question

I am creating a password generator program and was wondering which was more random, or if they're the same.

I randomly choose 1 or 0, if 1 it randomly picks a number between 1 and 26, that corresponds with a letter, if 0 it randomly picks a number between 1 and 10 that corresponds with a number 0-9.

Or I randomly choose a number between 1 and 36, with 1-26 being letters and 27-36 being a number.

pzifisssh · Accepted Answer

The second case, where you pick a number from 1-36, has more entropy (i.e., it is "more random") than the first case.  

http://en.wikipedia.org/wiki/Entropy_%28Information_theory%29

In the second case, every letter and every digit is equally likely to appear (one chance in 36) in a password.  In the first case, The likelihood of any given digit is one chance in 20, whereas the liklihood of a given letter is one in 52.

Anonymous · Answer

1/2 * 1/10 + 1/2 * 1/26 = 9/130
1/36

1/36 is a bigger number than 9/130.  I think I did the math right... probability is not a very strong subject with me.  But from what I can tell, randomly picking from 36 is a more difficult code to break

Anonymous · Answer

I'm not positive, but I think they're about the same.

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Which is mathematically more random?

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