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Back to Calculate the expected value of a random variable — Problem 1 · Task Set 28

Exercises: Calculate the Expected Value of a Random Variable

Work through each section in order. Compute expected value with
E(X)=∑x⋅P(X=x)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)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
Work through problems with immediate feedback
A

Fluency Practice

Compute each expected value as an explicit weighted sum. Write each term as value times its probability before adding.

1.

A spinner has three regions with the distribution below.

xx5820
P(X=x)P(X=x)1/21/41/4

Which computation gives the correct expected value E(X)E(X)?