how would you do a random variable problem like this

suppose a non bias coin was tossed two times

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- Dec 4th 2007, 10:54 PMjim1174Suppose a non bias coin was tossed two times?
how would you do a random variable problem like this

suppose a non bias coin was tossed two times - Dec 4th 2007, 11:06 PMDivideBy0
Well... let $\displaystyle x$ be the random variable. You could make it stand for the number of times heads appeared.

$\displaystyle Pr(X=x)$ would then be the probability that x heads appeared.

$\displaystyle Pr(X=0) = 1-\left(\frac{1}{2}\right)^2 = \frac{3}{4}$xxx

$\displaystyle Pr(X=1)=\frac{1}{2}$

$\displaystyle Pr(X=2) = \left(\frac{1}{2}\right)^2 = \frac{1}{4}$

Since the coin is non-biased these same probabilities would appear if you set $\displaystyle x$ as the number of tails that appeared.

Is this what you wanted? - Dec 5th 2007, 12:06 AMTwistedOne151Error
DividyBy0,

Shouldn't it be $\displaystyle Pr(X=0) = \left(1-\frac{1}{2}\right)^2 = \frac{1}{4}$, not $\displaystyle Pr(X=0) = 1-\left(\frac{1}{2}\right)^2 = \frac{3}{4}$ ?

--Kevin C. - Dec 5th 2007, 12:25 AMDivideBy0
yeah, you're right