Probability: Expected Value

In summary, a dice game involves rolling 2 dice and winning \$5 if you roll a 2, 3, 4, 10, 11, or 12, and losing \$5 if you roll a 5, 6, 7, 8, or 9. The expected value for this game is \$0.
  • #1
AnnBean
1
0
I really need help on how to solve this (Sweating):

A dice game involves rolling 2 dice. If you roll a 2, 3 , 4, 10, 11 or a 12, you win \$5. If you roll a 5, 6, 7, 8, or 9, you lose \$5. Find the expected value you win (or lose) per game.
 
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  • #2
Re: Probability

Hello, and welcome to MHB, AnnBean! (Wave)

I would begin by constructing a table as follows:

Sum $S$Probability of $S$: $P(S)$Net Gain/Loss (in dollars) $G$Product $G\cdot P(S)$
2$\dfrac{1}{36}$5$\dfrac{5}{36}$
3$\dfrac{1}{18}$5$\dfrac{5}{18}$

Can you complete the table?
 
  • #3
Re: Probability

Just to follow up, here is the completed table:

Sum $S$Probability of $S$: $P(S)$Net Gain/Loss (in dollars) $G$Product $G\cdot P(S)$
2$\dfrac{1}{36}$5$\dfrac{5}{36}$
3$\dfrac{1}{18}$5$\dfrac{5}{18}$
4$\dfrac{1}{12}$5$\dfrac{5}{12}$
5$\dfrac{1}{9}$-5$-\dfrac{5}{9}$
6$\dfrac{5}{36}$-5$-\dfrac{25}{36}$
7$\dfrac{1}{6}$-5$-\dfrac{5}{6}$
8$\dfrac{5}{36}$-5$-\dfrac{25}{36}$
9$\dfrac{1}{9}$-5$-\dfrac{5}{9}$
10$\dfrac{1}{12}$5$\dfrac{5}{12}$
11$\dfrac{1}{18}$5$\dfrac{5}{18}$
12$\dfrac{1}{36}$5$\dfrac{5}{36}$

Summing up the $G\cdot P(S)$, column, we find the expected value is:

\(\displaystyle \text{EP}=-\frac{5}{3}\)
 

1. What is the definition of expected value in probability?

The expected value in probability is a measure of the average outcome of a random variable. It is calculated by multiplying each possible outcome by its probability and then summing all of these values together.

2. How is expected value used in decision making?

Expected value is used in decision making as a way to quantify the potential gains or losses of a certain action. It helps individuals or businesses make informed decisions by considering all possible outcomes and their corresponding probabilities.

3. Can expected value be negative?

Yes, expected value can be negative. This means that the potential outcome of a certain action has a higher probability of resulting in a loss rather than a gain. It is important to consider the expected value when making decisions, as it takes into account both the potential gains and losses.

4. How does sample size affect expected value?

Sample size does not directly affect the expected value, but it can affect the accuracy of the expected value. With a larger sample size, the expected value will be a more accurate representation of the true average outcome. However, even with a small sample size, the expected value can still provide valuable insights.

5. How is expected value different from actual value?

Expected value is a calculated measure based on the probabilities of possible outcomes, while actual value is the real outcome that occurs. Expected value helps us make decisions by considering all potential outcomes, while actual value reflects the specific outcome that has occurred.

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