High School

Calculate the expected value of \(X\), \(E(X)\), for the given probability distribution.

\[
\begin{array}{c|c|c|c|c}
X & 10 & 20 & 30 & 40 \\
\hline
p(X=x) & \frac{15}{20} & \frac{20}{50} & \frac{5}{50} & \frac{10}{50} \\
\end{array}
\]

Answer :

Final answer:

The expected value E(X) for the given probability distribution is calculated by multiplying each value of X by its probability, then adding up the products. In this case, E(X) = 26.5.

Explanation:

To calculate the expected value of X, E(X), for the given probability distribution, we use the formula E(X) = μ = Σ xP(x), where μ is the mean, x is each value of the random variable, and P(x) is the probability of x occurring. The expected value represents the long-term average if the experiment is repeated many times. Here is the calculation step by step:


  • Multiply each value of X by its probability: (10 * 15/20) + (20 * 20/50) + (30 * 5/50) + (40 * 10/50).

  • Simplify and calculate each product: (10 * 0.75) + (20 * 0.40) + (30 * 0.10) + (40 * 0.20).

  • Add up all the products: 7.5 + 8 + 3 + 8.

  • Calculate the sum to find E(X): 7.5 + 8 + 3 + 8 = 26.5

Therefore, the expected value of X, E(X), is 26.5.