A game at the fair involves a wheel with seven sectors. Two of the sectors are red, two of the sectors are purple, two of the sectors are yellow, and one sector is blue.

- Landing on the blue sector will give 3 points.
- Landing on a yellow sector will give 1 point.
- Landing on a purple sector will give 0 points.
- Landing on a red sector will give -1 point.

a. Let [tex]$X$[/tex] be the points you have after one spin. Fill out the missing values in the table. (5 points)

b. If you take one spin, what is your expected value? (5 points)



Answer :

Sure, let's solve the problem step by step.

### a. Filling out the Missing Values in the Table

First, we need to determine the probabilities for each colored sector.

- The wheel has 7 sectors in total.
- There are 2 red sectors out of 7, so the probability of landing on a red sector (P(Red)) is [tex]\( \frac{2}{7} \)[/tex].
- There are 2 purple sectors out of 7, so the probability of landing on a purple sector (P(Purple)) is [tex]\( \frac{2}{7} \)[/tex].
- There are 2 yellow sectors out of 7, so the probability of landing on a yellow sector (P(Yellow)) is [tex]\( \frac{2}{7} \)[/tex].
- There is 1 blue sector out of 7, so the probability of landing on a blue sector (P(Blue)) is [tex]\( \frac{1}{7} \)[/tex].

Now we create the table with the points for each color and their corresponding probabilities:

| Color | Points | Probability |
|--------|--------|--------------------|
| Red | -1 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Purple | 0 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Yellow | 1 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Blue | 3 | [tex]\( \frac{1}{7} \)[/tex] ≈ 0.14285714285714285 |

### b. Calculating the Expected Value

To find the expected value of the points after one spin, we use the formula for the expected value of a discrete random variable:
[tex]\[ E(X) = \sum (x_i \cdot P(x_i)) \][/tex]
where [tex]\( x_i \)[/tex] is the number of points for each sector, and [tex]\( P(x_i) \)[/tex] is the probability of landing on that sector.

Let's break it down:

- For Red: Points = -1, Probability = [tex]\( \frac{2}{7} \)[/tex]
- For Purple: Points = 0, Probability = [tex]\( \frac{2}{7} \)[/tex]
- For Yellow: Points = 1, Probability = [tex]\( \frac{2}{7} \)[/tex]
- For Blue: Points = 3, Probability = [tex]\( \frac{1}{7} \)[/tex]

Now, we calculate the expected value:
[tex]\[ E(X) = (-1 \cdot \frac{2}{7}) + (0 \cdot \frac{2}{7}) + (1 \cdot \frac{2}{7}) + (3 \cdot \frac{1}{7}) \][/tex]

Calculating each term separately:
[tex]\[ -1 \cdot \frac{2}{7} = -\frac{2}{7} \][/tex]
[tex]\[ 0 \cdot \frac{2}{7} = 0 \][/tex]
[tex]\[ 1 \cdot \frac{2}{7} = \frac{2}{7} \][/tex]
[tex]\[ 3 \cdot \frac{1}{7} = \frac{3}{7} \][/tex]

Adding these together:
[tex]\[ E(X) = -\frac{2}{7} + 0 + \frac{2}{7} + \frac{3}{7} = \frac{3}{7} \][/tex]

Therefore, the expected value for one spin is:
[tex]\[ E(X) = \frac{3}{7} ≈ 0.42857142857142855 \][/tex]

### Summary

- a. The table with the missing values:
| Color | Points | Probability |
|--------|--------|--------------------|
| Red | -1 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Purple | 0 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Yellow | 1 | [tex]\( \frac{2}{7} \)[/tex] ≈ 0.2857142857142857 |
| Blue | 3 | [tex]\( \frac{1}{7} \)[/tex] ≈ 0.14285714285714285 |

- b. The expected value after one spin is:
[tex]\[ E(X) ≈ 0.42857142857142855 \][/tex]