Expectation value and variance

Felicia

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Apr 14, 2019
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Two fair dice are tossed. If the total score is 5 or more Alfred pays $x to Bernice. If the total score is 4 or less Bernice pays $(x-8) to Alfred. Calculate Alfred’s expectation value after the first throw in terms of x. If x=3 what is Alfred’s variance after the first throw.
 
Can you please show us what you tried? It is extremely hard to help you arrive at the correct answer if we do not know where you are making your mistake(s). Thanks.
 
This is the exact question stuck at last part. For variance e(x^2)-e(x)^2 or (x-mean)^2
 
This is the exact question stuck at last part. For variance e(x^2)-e(x)^2 or (x-mean)^2
It is standard form for expected value to use "E", not "e'. Avoid confusion.

Mean: E(x)
Variance: E(x^2) - [E(x)]^2
When there is another formula for either, please use it when it is more convenient.
 
What is the formula for E(x)? Which values can x take on? What is p(x) for each x value?
 
What does "after the first throw" mean? Are we throwing one die, calculating mean and variance, and then throwing the second die?
 
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