Back to Calculate the expected value of a random variable — Problem 3 · Task Set 28
Exercises: Calculate the Expected Value of a Random Variable
Work through each section in order. Compute expected value with $E(X) = \sum x \cdot P(X = x)$: multiply each value by its probability, then add. Show each term as "value times its probability" before summing. For payoff problems, write losses as negative values. Remember that $E(X)$ is the mean of the distribution and need NOT be a value the variable can actually take.
Grade 11·22 problems·~35 min·Common Core Math - HS Statistics and Probability·group·hss-md-a-2
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Warm-Up: Distributions and Weighted Means
These problems review probability distributions and the weighted-average idea you already know.
1.
A fair four-sided die shows the values , each with probability . Because all outcomes are equally likely, is just the plain average of the values. Compute .