Question about calculating probability.

[Ruban]

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Ok, so this is probably a very easy question for someone who knows statistics, but:

Let's say the chance of getting a disease is 20% (0.2)
Then, I choose 10 people at random from the population. What is the chance that one will have the disease.

I want to say it's just .2 * 10 = 2

But I thought probabilities had to be less than 1, since if there is a 100% probability of something happening, it will definitely happen. So a 200% probability would be meaningless.

Thoughts?

Thanks!

 

[Wrigleyville]

The probability that at least one person gets it is 1 - probability that no one gets it:

1 - (0.8)^10