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What is expected value?

Updated: 11/19/2022
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6y ago

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If this is regarding probability, there are two cases:

E[Y] = (Summation) yp(y) in the discrete case. For example a fair dice has 1/6 probabilty for each event (of getting one value). so the sum is from 1 to 6 of yp(y). = 1(1/6) + 2(1/6) + 3(1/6) + 4(1/6) + 5(1/6) + 6(1/6) = (1/6) ( 1+2+3+4+5+6) = 21/6 = 3.5. So E[Y] for a fiar dice is 3.5

E[Y]= (intergral from -infinity to infinity) yf(y)dy , where f(y) is the density function for the continuous case. The integral must exits to be evaluated.

The difference between the two is basically the domain. If you dealing with integers you can use the discrete case, if you dealing with real numbers you have to use calculus.

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12y ago
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6y ago

It is the average (arithmetic mean) value of a variable that you would expect to get if the relevant experiment were repeated many times.

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