Financial Expectation2021-01-01T11:30:31+10:00

Timetable Forums Standard Probability & Relative Frequency Financial Expectation

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    Expected Value & Frequency

    Expected Value= The sum of the (probability × outcome)

    Expected frequency = probability of event occurring × number of trials

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    It costs $12 to play a game. There is a probability of $$\frac14$$ of winning $40 and a probability of $$\frac38$$ of winning $25. Calculate the financial expectation of this game.

    P(lose) = $$1-\frac14-\frac38=\frac38$$

    E = $$\frac14\times\,$40+\frac38\times\,$25-\frac38\times\,$10-$12$$    (don’t forget to subtract the cost of playing the game)

    = $3.625

    ∴ E = $3.63

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    A game is played by tossing two coins. The rules are: If two heads are thrown you win $10. If two heads are not thrown you lose $5.
    a. Determine the financial expectation for this game.

    b. If you played this game 50 times, how much would you expect to win or lose?

    a. P(2 heads) = ¼  P(not 2 heads) = ¾

    E = ¼ × 10 + ¾ × -5
    E = -1.25
    Lose $1.25

    b. n = 50
    E = 50 × -1.25

    = -62.5

    ∴ lose $62.50

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    In a raffle, 1000 tickets are sold costing $2 each. First prize is $350, second prize is $175, third prize is $100 and fourth prize is $50. No ticket can win more than one prize. What is the probability of winning first prize? What is the expected financial return?

    P(win first prize) = 1/1000
    P(1st) = 1/1000
    P(2nd) = 1/1000
    P(3rd) = 1/1000
    P(no prize) = 997/1000

    E = 1/1000 × 250 + 1/1000 × 125 + 1/1000 × 100 + 997/1000 × -2
    E = -1.519
    ∴ lose $1.52

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    Amy buys a $1 ticket in a raffle. There are 200 tickets in the raffle and two prizes. First prize is $100 and second prize is $50. Find Amy’s financial expectation.

    1st prize = 1/200 × 100
    = $0.50
    2nd prize = 1/200 × 50
    = $0.25
    No prize = 198/100 × -1
    = -$0.99

    total = 50 + 25 – 99 = -24

    ∴ loss of $0.24

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    There is a game where there is a 20% chance of winning $50, 50% chance of winning $5 or losing $5 if no prize is won. What is the financial expectation of this game?

    P(lose) = 0.3

    E = 0.20 × $50 + 0.50 × $5 + 0.30 × -$5

    = $11

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    A coin is biased to that there is a 60% chance it will be heads when it is tossed.  If the coin is tossed and the result is “a head” you win $12 if the result is “a tail” you lose $15. Calculate the expected financial return.
    P(H) = 0.6  win $12
    P(T) = 0.4  lose $15
    To obtain the Expectation (E) you must multiply the probability of the outcome by the financial return, remembering if it is a loss, then the number is negative
    E = 0.6 × 12 + 0.4 × -15
    = $1.20
    so the expectation of the game is positive, which is a win, of $1.20
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    John plays a game in which he has a 20% chance of winning $50, a 50% chance of winning $10 and a 30% chance of losing $5. What is John’s financial expectation when playing this game?
    P($50) = 0.2
    P($10) = 0.5
    P(-$5) = 0.3
    each probability must be multiplied by the outcome, and the loss will be a negative outcome
    E = 0.2 × 50 + 0.5 × 10 + 0.3 × -5
    E = $13.50
    calculate the expectation, which in this case is winning  $13.50
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