(adsbygoogle = window.adsbygoogle || []).push({}); Problem:

We play roulette in a casino. We watch 100 rounds that result in a number between 1 and 36. and count the number of rounds for which the result is odd.

assuming that the roulette is fair, calculate the mean and deviation

Solution:

I understand that the probability - Pr = 0.5. and mean - E[x] = 50. However, I cant figure out how to write it appropriately (use formula E[x] = ∑ x * Pr)

As I Understand, I must choose random variable x = 1, but don't quite understand the "true" meaning of it and why I can't choose other variable.

Moreover, I see from solutions that σ_{s}=√(100 * 0.5 * 0.5) = 5. However, I cant understand how we get this

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# B Random Variable - Mean and Variance

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