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Find the expected value of the random variable with the given probability distribution.

[tex]\[
\begin{array}{r|c}
x & P(x) \\
\hline
-1 & 0.05 \\
1 & 0.18 \\
3 & 0.21 \\
5 & 0.23 \\
7 & 0.14 \\
9 & 0.19 \\
\end{array}
\][/tex]


Sagot :

Sure, let's find the expected value of the random variable, given its probability distribution.

1. Identify the values of the random variable [tex]\(x\)[/tex]:
[tex]\[ x = [-1, 1, 3, 5, 7, 9] \][/tex]

2. Identify the corresponding probabilities [tex]\(P(x)\)[/tex]:
[tex]\[ P = [0.05, 0.18, 0.21, 0.23, 0.14, 0.19] \][/tex]

3. Recall the formula for the expected value [tex]\(\mathbb{E}(X)\)[/tex] of a discrete random variable:
[tex]\[ \mathbb{E}(X) = \sum_{i=1}^{n} x_i \cdot P(x_i) \][/tex]
where [tex]\(x_i\)[/tex] are the values of the random variable and [tex]\(P(x_i)\)[/tex] are the corresponding probabilities.

4. Plug in the values and their probabilities into the formula:

[tex]\[ \mathbb{E}(X) = (-1) \cdot 0.05 + 1 \cdot 0.18 + 3 \cdot 0.21 + 5 \cdot 0.23 + 7 \cdot 0.14 + 9 \cdot 0.19 \][/tex]

5. Calculate each term individually:

[tex]\[ -1 \cdot 0.05 = -0.05 \][/tex]
[tex]\[ 1 \cdot 0.18 = 0.18 \][/tex]
[tex]\[ 3 \cdot 0.21 = 0.63 \][/tex]
[tex]\[ 5 \cdot 0.23 = 1.15 \][/tex]
[tex]\[ 7 \cdot 0.14 = 0.98 \][/tex]
[tex]\[ 9 \cdot 0.19 = 1.71 \][/tex]

6. Add all these terms together to find the expected value:

[tex]\[ \mathbb{E}(X) = -0.05 + 0.18 + 0.63 + 1.15 + 0.98 + 1.71 = 4.60 \][/tex]

Therefore, the expected value of the random variable is [tex]\( \boxed{4.60} \)[/tex].