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# help

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Suppose we have a bag with 10 slips of paper in it. Eight of these have a 2 on them and the other two have a 4 on them.

What is the expected value of the number shown when we draw a single slip of paper?

Nov 24, 2018

#2
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Expected value is computed by multiplying all of the possible outcomes by their probabilities, and then summing. $$8/10$$ of the time we draw a 2 and $$2/10$$ of the time we draw a 4. Therefore the expected value is

$$2\cdot\frac{8}{10} + 4\cdot\frac{2}{10} = \frac{12}{5}.$$

Nov 24, 2018

#1
+2

$$P=\dfrac{8}{10}=\dfrac{4}{5}\\ P = \dfrac 1 5\\ E[N] = 8\cdot 2 \cdot \dfrac 4 5 + 2 \cdot 4 \cdot \dfrac 1 5 = \\ \dfrac{64}{5} + \dfrac 8 5 = \dfrac{72}{5}$$

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Nov 24, 2018
#2
+2
Expected value is computed by multiplying all of the possible outcomes by their probabilities, and then summing. $$8/10$$ of the time we draw a 2 and $$2/10$$ of the time we draw a 4. Therefore the expected value is
$$2\cdot\frac{8}{10} + 4\cdot\frac{2}{10} = \frac{12}{5}.$$