Use Scenario 6-5.Consider the following game.You pay me an entry fee of x dollars; then I roll a fair die. If the die shows a number less than 3 I pay you nothing; if the die shows a 3 or 4, I give you back your entry fee of x dollars; if the die shows a 5, I will pay you $1; and if the die shows a 6, I pay you $3. What value of x makes the game fair (in terms of expected value) for both of us?
A.$2
B.$4
C.$1
D.$0.75
E.$0.5

Respuesta :

Answer:

C.$1

Step-by-step explanation:

Since, when a die is rolled,

Then the total possible outcomes = 6 ( i.e. 1, 2, 3, 4, 5 or 6 )

Outcomes of getting number less than 3 = 2 ( i.e. 1 or 2 )

Outcomes of getting  3 or 4 = 2

Outcomes of getting 5 = 1,

Outcomes of getting 6 = 1,

[tex]\because \text{Probability}=\frac{\text{Favourable outcomes}}{\text{Total outcomes}}[/tex]

Thus, the probability of getting number less than 3 = [tex]\frac{2}{6}=\frac{1}{3}[/tex]

The probability of getting 3 or 4 = [tex]\frac{2}{6}=\frac{1}{3}[/tex]

The probability of getting 5 = [tex]\frac{1}{6}[/tex]

The probability of getting 6 = [tex]\frac{1}{6}[/tex]

∵ If the die shows a number less than 3 then nothing will get; if the die shows a 3 or 4, we will get x dollars; if the die shows a 5, we will get $1; and if the die shows a 6, we will get $3

So, the expected value = [tex]x\times \frac{1}{3}+0\times \frac{1}{3}+1\times \frac{1}{6}+3\times \frac{1}{6}[/tex]

[tex]=\frac{x}{3}+\frac{1}{6}+\frac{1}{2}[/tex]

[tex]=\frac{2x+1+3}{6}[/tex]

[tex]=\frac{2x+4}{6}[/tex]

The game is fair if,

[tex]\frac{2x+4}{6}=x[/tex]

[tex]2x + 4 = 6x[/tex]

[tex]4 = 4x[/tex]

[tex]\implies x = 1[/tex]

Hence, the value of x would be $ 1.

The value of [tex]x[/tex] would be [tex]\$ 1[/tex]

Total possible outcomes when a die is rolled [tex]=6 (i.e, 1,2,3,4,5\; or \; 6)[/tex]

Outcomes of getting number less than [tex]3=2 ( i.e, 1\; or \;2)[/tex]

Outcomes of getting [tex]3\; or\; 4=2[/tex],

Outcomes of getting [tex]5=1,[/tex]

Outcomes of getting [tex]6=1,[/tex]

[tex]Probability=\dfrac{Favourable\; outcomes}{Total\; number\; of\; outcomes}[/tex]

Thus, the probability of getting number less than [tex]3 = \dfrac{2}{6}[/tex]

                                                                                      [tex]=\dfrac{1}{3}[/tex]

The probability of getting [tex]3\; or \;4 = \dfrac{2}{6}[/tex]

                                                      [tex]=\dfrac{1}{3}[/tex]

The probability of [tex]5=\dfrac{1}{6}[/tex]

The probability of [tex]6=\dfrac{1}{6}[/tex]

∴ According to question If the die show a number less than [tex]3[/tex] then nothing will be paid, if the die shows a [tex]3\;or\;4[/tex], we get [tex]x[/tex] dollars; if the die shows a [tex]5[/tex] , we get  [tex]\$ 1[/tex]; and if the die shows a [tex]6[/tex], we will get [tex]\$ 3[/tex]

So Expected value [tex]=x\times \dfrac{1}{3} + 0\times \dfrac{1}{3} + 1\times \dfrac{1}{6} +3\times \dfrac{1}{6} \\[/tex]

                                [tex]=x\times \dfrac{1}{3} + \dfrac{1}{6} + \dfrac{1}{2}[/tex]

                                 [tex]= \dfrac{2x+1+3}{6}[/tex]

The game is fair if,

[tex]\dfrac{2x+4}{6}=x[/tex]

[tex]2x+4=6x[/tex]

       [tex]4=4x[/tex]

        [tex]x=1[/tex]

Therefore , the value of [tex]x[/tex] would be [tex]\$ 1[/tex]

Hence option c is correct.

Learn more about probability concept here;

https://brainly.com/question/23044118?referrer=searchResults