Expected value and probability distributions worksheet for Statistics
Statistics treats expected value as the mean of a discrete random variable, the long-run average over many trials. Check first that the probabilities add to 1, then weight each outcome by its probability. Games, raffles and insurance policies are judged by whether that mean is positive, negative or zero, and zero is a fair game.
Also taught in Algebra 2 and Precalculus, each at its own level and with its own examples.
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Find the expected value.xP(x)13161683−2161121
Find the expected value.xP(x)−141−521−2811081
Find the expected value.xP(x)−385781−181−481
Find the expected value.xP(x)17165−21611016911161
Find the expected value.xP(x)18515811881281
Find the expected profit or fair price
A ring toss costs $4.00 for one throw, which wins a prize of $15.48 with probability 61, or nothing; the $4.00 is not given back. What price for one throw would make the expected profit zero?
A game costs $5.00 to play. It pays out a prize of $13.20 with probability 21, and otherwise nothing; the $5.00 is not returned. Someone pays for 20 plays. Find their expected total profit.
A raffle ticket costs $5.00. It wins a prize of $15.68 with probability 81, and nothing otherwise; the ticket price is not returned. Find the expected profit of one ticket for the player.
A prize wheel at a fair costs $4.00 a spin. A spin wins a prize of $34.40 with probability 207 and a prize of $3.40 with probability 41, and otherwise nothing; the $4.00 is kept. What price for one spin would make the expected profit zero?
A scratch card sells for $4.00. It pays out a prize of $25.00 with probability 21;the $4.00 is not refunded. Someone pays for 25 cards. Find their expected total profit.
Find the missing probability
Find the missing probability.outcomePA41B167C163D?
Find the missing probability.outcomePA121B61C?D125
Find the missing probability.outcomePA?B121C61D127
Find the missing probability.outcomePA161B?C167D161
Find the missing probability.outcomePA?B61C61D121
Find the mean and standard deviation
A bag holds 10 tickets: 2 marked 0, 3 marked 10, 1 marked 20 and 4 marked 30. One ticket is drawn at random, and X is the number on it. What are the mean and the standard deviation of X? Round to the nearest hundredth.
Let X be the change in a stock price, in dollars, over one day. One probability is missing from the table. Calculate the mean μof X and its standard deviation σ, to the nearest hundredth.xP(x)−20.1−1?00.410.3
Let X be the number of goals a team scores in a game. It takes the values 0, 1, 2 and 3 with probabilities 0.3, 0.1, 0.3 and 0.3, in that order. Work out μand σfor X, to the nearest hundredth.
Let X be the number of tries a student needs to pass a driving test. Give the expected value and the standard deviation of X, each to the nearest hundredth.xP(x)10.420.430.140.1
Let X be the number of books a student borrows on a library visit. One probability is missing from the table. Find its expected value μ and its standard deviation σ, to the nearest hundredth.xP(x)10.120.130.34?
Expected Value and Probability DistributionsAnswer keyVersion 3
Date Period
Answer each question.
Find the expected value from a table
Find the expected value.xP(x)13161683−21611211655
Find the expected value.xP(x)−141−521−2811081−47
Find the expected value.xP(x)−385781−181−481−813
Find the expected value.xP(x)17165−21611016911161223
Find the expected value.xP(x)185158118812815
Find the expected profit or fair price
A ring toss costs $4.00 for one throw, which wins a prize of $15.48 with probability 61, or nothing; the $4.00 is not given back. What price for one throw would make the expected profit zero?$2.58
A game costs $5.00 to play. It pays out a prize of $13.20 with probability 21, and otherwise nothing; the $5.00 is not returned. Someone pays for 20 plays. Find their expected total profit.$32.00
A raffle ticket costs $5.00. It wins a prize of $15.68 with probability 81, and nothing otherwise; the ticket price is not returned. Find the expected profit of one ticket for the player.−$3.04
A prize wheel at a fair costs $4.00 a spin. A spin wins a prize of $34.40 with probability 207 and a prize of $3.40 with probability 41, and otherwise nothing; the $4.00 is kept. What price for one spin would make the expected profit zero?$12.89
A scratch card sells for $4.00. It pays out a prize of $25.00 with probability 21;the $4.00 is not refunded. Someone pays for 25 cards. Find their expected total profit.$212.50
Find the missing probability
Find the missing probability.outcomePA41B167C163D?81
Find the missing probability.outcomePA121B61C?D12531
Find the missing probability.outcomePA?B121C61D12761
Find the missing probability.outcomePA161B?C167D161167
Find the missing probability.outcomePA?B61C61D121127
Find the mean and standard deviation
A bag holds 10 tickets: 2 marked 0, 3 marked 10, 1 marked 20 and 4 marked 30. One ticket is drawn at random, and X is the number on it. What are the mean and the standard deviation of X? Round to the nearest hundredth.μ=17,σ≈11.87
Let X be the change in a stock price, in dollars, over one day. One probability is missing from the table. Calculate the mean μof X and its standard deviation σ, to the nearest hundredth.xP(x)−20.1−1?00.410.3μ=−0.1,σ≈0.94
Let X be the number of goals a team scores in a game. It takes the values 0, 1, 2 and 3 with probabilities 0.3, 0.1, 0.3 and 0.3, in that order. Work out μand σfor X, to the nearest hundredth.μ=1.6,σ≈1.20
Let X be the number of tries a student needs to pass a driving test. Give the expected value and the standard deviation of X, each to the nearest hundredth.xP(x)10.420.430.140.1μ=1.9,σ≈0.94
Let X be the number of books a student borrows on a library visit. One probability is missing from the table. Find its expected value μ and its standard deviation σ, to the nearest hundredth.xP(x)10.120.130.34?μ=3.2,σ≈0.98
An insurer charges $300 for a policy that pays $20,000 with probability 0.01. Find the insurer's expected profit
Expected payout: 20000 × 0.01 = 200.
Profit is the premium minus the expected payout: 300 - 200.
The answer is $100.00.
Where students go wrong
Subtracting the cost twice. If a ticket costs $5 and pays $50, either use a net gain of $45 on a win and -$5 on a loss, or subtract $5 once from the expected payout, but not both.
Also called probability distributions, expected payoff, fair games or discrete random variables.
What you can put on this worksheet
Expected value from a table
Find the expected value. xP(x)152352451→ 512
Expected profit of a game
A scratch card sells for $2.00. It pays out a prize of $2.40 with probability 52;the $2.00 is not refunded. Find the expected prize money per card, before the price is taken off.→ $0.96
The missing probability
Find the missing probability. outcomePA?B52C51→ 52
Mean and standard deviation
A bag holds 10 tickets: 2 marked 0, 5 marked 10 and 3 marked 20. One ticket is drawn at random, and X is the number on it. Calculate the mean μof X and its standard deviation σ, to the nearest hundredth.→ μ=11,σ≈7.00
Questions about these worksheets
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Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.
Statistics is usually taken around 11th or 12th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.
Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.
That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the expected value and probability distributions questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.
Yes. There are three levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.
You pick from 4: expected value from a table, expected profit of a game, the missing probability and mean and standard deviation. Tick as many as you want and set how many of each, or let it spread them evenly.
Forgetting the cost, or forgetting that the probabilities have to add to 1 before a missing one can be found.