Use the fact that the mean of a geometric distribution is μ= 1 p and the variance is σ2= q p2. A daily number lottery chooses three balls numbered 0 to 9. The probability of winning the lottery is 1 1000. Let x be the number of times you play the lottery before winning the first time. ​(a) Find the​ mean, variance, and standard deviation.​ (b) How many times would you expect to have to play the lottery before​ winning? It costs​ $1 to play and winners are paid ​$500. Would you expect to make or lose money playing this​ lottery? Explain.

Respuesta :

Answer:

a). The mean = 1000

     The variance = 999,000

     The standard deviation = 999.4999

b). 1000 times , loss

Step-by-step explanation:

The mean of geometric distribution is given as , [tex]$\mu = \frac{1}{p}$[/tex]

And the variance is given by, [tex]$\sigma ^2=\frac{q}{p^2}$[/tex]

Given : [tex]$p=\frac{1}{1000}$[/tex]

             = 0.001

The formulae of mean and variance are :

[tex]$\mu = \frac{1}{p}$[/tex]

[tex]$\sigma ^2=\frac{q}{p^2}$[/tex]

[tex]$\sigma ^2=\frac{1-p}{p^2}$[/tex]

a). Mean =   [tex]$\mu = \frac{1}{p}$[/tex]

              = [tex]$\mu = \frac{1}{0.001}$[/tex]

              = 1000

  Variance =   [tex]$\sigma ^2=\frac{1-p}{p^2}$[/tex]

                  = [tex]$\sigma ^2=\frac{1-0.001}{0.001^2}$[/tex]

                           = 999,000

   The standard deviation is determined by the root of the variance.

    [tex]$\sigma = \sqrt{\sigma^2}$[/tex]

        = [tex]$\sqrt{999,000}$[/tex] = 999.4999

b). We expect to have play lottery 1000  times to win, because the mean in part (a) is 1000.

When we win the profit is 500 - 1 = 499

When we lose, the profit is -1

Expected value of the mean μ is the summation of a product of each of the possibility x with the probability P(x).

[tex]$\mu=\Sigma\ x\ P(x)= 499 \times 0.001+(-1) \times (1-0.001)$[/tex]

  = $ 0.50

Since the answer is negative, we are expected to make a loss.

The mean, variance, and standard deviation will be 1000, 999000, and 999.50 respectively.

Based on the information given, the mean will be:

= 1/p = 0.001 = 1000

The variance will be calculated as:

= (1 - 0.001) / 0.001²

= 999,000

The standard deviation will be;

= ✓999000

= 999.50

Lastly, the number of times that the person will expect to play before winning will be 1000 times and when there's a loss, the amount will be -1 and a winning brings a profit of $499.

Learn more about mean on:

https://brainly.com/question/20118982

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