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A charity is holding a raffle to raise money. There is one car worth [tex]$30,000. Each ticket costs $[/tex]20, and there are a total of 5,000 tickets being sold. Which calculation represents the expected value for a ticket?

A. [tex]\(30,000\left(\frac{1}{5000}\right) + 100\left(\frac{1}{1000}\right) + (-20)\left(\frac{2497}{2500}\right) - E(X)\)[/tex]

B. [tex]\(29,980\left(\frac{1}{5000}\right) + 80\left(\frac{1}{1000}\right) + (-20)\left(\frac{2497}{2500}\right) = E(X)\)[/tex]

C. [tex]\(30,000\left(\frac{1}{5000}\right) + 100\left(\frac{1}{1000}\right) = E(X)\)[/tex]

D. [tex]\(29,980\left(\frac{1}{5000}\right) + 80\left(\frac{1}{1000}\right) - E(X)\)[/tex]


Sagot :

Sure, let's proceed step-by-step to calculate the expected value for a ticket in this raffle scenario.

1. Determine the Probability of Winning and Losing:
- Probability of Winning the Car: Since there is only one car and 5,000 tickets are sold, the probability of winning the car is given by:
[tex]\[ \text{Probability of Winning} = \frac{1}{5000} = 0.0002 \][/tex]

- Probability of Losing: If you do not win the car, you lose. Thus, the probability of losing is:
[tex]\[ \text{Probability of Losing} = 1 - \text{Probability of Winning} = 1 - 0.0002 = 0.9998 \][/tex]

2. Determine the Values Associated with Winning and Losing:
- Value if Win: If you win, you get the car worth [tex]$30,000. Thus, the value of winning can be stated as: \[ \text{Value if Win} = 30,000 \] - Value if Lose: If you lose, you are out the cost of the ticket, which is $[/tex]20. Thus, the value of losing is:
[tex]\[ \text{Value if Lose} = -20 \][/tex]

3. Expected Value Calculation:
- The expected value (EV) of a ticket can be calculated using the formula:
[tex]\[ EV = (\text{Value if Win} \times \text{Probability of Winning}) + (\text{Value if Lose} \times \text{Probability of Losing}) \][/tex]

Plug in the values:
[tex]\[ EV = (30,000 \times 0.0002) + (-20 \times 0.9998) \][/tex]

Simplify the terms:
[tex]\[ EV = 6 - 19.996 \][/tex]

[tex]\[ EV = -13.996 \][/tex]

Hence, the expected value (EV) for a ticket in this raffle is:
[tex]\[ -13.996 \][/tex]

Therefore, among the given options, none of them directly represent the correct calculation or expected value [tex]$-13.996$[/tex].

The correct calculation should be:

[tex]\[ 30,000 \left( \frac{1}{5000} \right) + (-20) \left( \frac{4999}{5000} \right) = E(X) \][/tex]
[tex]\[ \left( 30,000 \times 0.0002 \right) + (-20 \times 0.9998) = E(X) \][/tex]

This confirms that the expected value of purchasing a ticket in this raffle is approximately [tex]$-13.996$[/tex].