I admit to being something of a math moron (glazed-over eyes in every math class I ever attended as a kid).....so while I'm certain that this is a fairly simple calculation, I would really appreciate help with the following.

While it may seem ridiculous, I need to determine the odds of an occurrence, in the following scenario.

A random selection from 650,000 possible choices matches a random selection from 750 billion choices. The resulting match would be 1 in ?????

Thanks in advance!

e

1 in 750 billion.

Not enough information was provided to answer the question.

What's missing?


Posted: Apr 22, 2010 6:50pm
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Actually, I just re-checked my figures and, as if I needed to reconfirm my lack of number prowess, I got one of them wrong!

Correction (and hopefully clarification):

The first selection is 1 in 650,000. The result of that then matches a 1 in 750 million (not billion) selection.

So, the odds of the first selection matching the final selection are?

Do the 650,000 selections form a subset of the 750,000,000 selections?
If you're selecting one out of a group of 650,000 New Yorkers...and then selecting one out of a group of 750 million residents of China, the probability of getting a "match" is 0.
(I'm only guessing what you mean by "match.")

If you're randomly selecting an integer out of the set {1, 2, 3, ..., 650000}
and then randomly selecting an integer out of the set {1, 2, ..., 750000000),
then the probability of a match is
1/750,000,000 (as Philemon pointed out.)

If the two sets overlap differently, you'll get a different answer.