Mathematics
Grade 11
15 min
Expected values for a game of chance
Expected values for a game of chance
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1
Introduction & Learning Objectives
Learning Objectives
Define the concept of expected value in the context of probability.
Construct a probability distribution table for a simple game of chance.
Calculate the expected value of a discrete random variable using the appropriate formula.
Interpret the meaning of a positive, negative, or zero expected value.
Analyze the 'fairness' of a game by calculating its expected value.
Apply the concept of expected value to make strategic decisions in scenarios involving risk and reward.
Ever wondered if that carnival spinner game is *really* worth the $2 ticket? 🎡 Let's use math to see if the odds are truly in your favor!
This tutorial introduces 'Expected Value', a powerful tool for predicting the long-term average outcome of a random event. You...
2
Key Concepts & Vocabulary
TermDefinitionExample
Random Variable (X)A variable whose value is a numerical outcome of a random phenomenon. It links numerical values to the outcomes of an experiment.In a game where you roll a standard six-sided die, the random variable X could be the number that appears on the top face (X can be 1, 2, 3, 4, 5, or 6).
Probability DistributionA table, graph, or formula that provides the probability for each possible value of a random variable.For a fair six-sided die, the probability distribution is P(X=1)=1/6, P(X=2)=1/6, ..., P(X=6)=1/6.
Outcome Value (x)The numerical value, or payoff, associated with a specific outcome of a game. This can be a gain (positive) or a loss (negative).In a coin toss game, you win $5 for heads (x = +5) and lose $5 for tails (x = -5).
Expected Value (E(X))...
3
Core Formulas
Expected Value Formula
E(X) = \sum_{i=1}^{n} x_i P(x_i)
To find the expected value, multiply each possible outcome value (x_i) by its corresponding probability (P(x_i)), and then sum all these products. This gives the weighted average outcome.
Sum of Probabilities
\sum_{i=1}^{n} P(x_i) = 1
The sum of the probabilities for all possible outcomes in a probability distribution must always equal 1. This is a crucial check to ensure your probability distribution is correct before calculating expected value.
4 more steps in this tutorial
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Easy
What does the expected value of a game of chance represent?
A.The long-term average outcome if the game is played many times.
B.The most likely outcome in a single play of the game.
C.The total amount of money a player can possibly win.
D.The probability of winning the game.
Easy
According to the tutorial, a game is considered 'fair' if its expected value is what?
A.large positive number
B.Zero
C.small negative number
D.Equal to the cost to play
Easy
Which formula correctly calculates the expected value, E(X), for a random variable X with outcomes xáµ¢ and probabilities P(xáµ¢)?
A.E(X) = Σ P(xᵢ)
B.E(X) = Σ (xᵢ + P(xᵢ))
C.E(X) = Σ [xᵢ * P(xᵢ)]
D.E(X) = Σ xᵢ / n
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