A box contains five black and five yellow balls. Two balls are withdrawn randomly. If they are of the same colour, then you win $1.10; if they are of different colours, then you lose $1.00. Calculate
i. the expected value of the amount you win
ii. the variance of the amount you win.

Respuesta :

Using a discrete probability distribution to model the situation, we have that:

i. The expected value of the amount you win is of -$0.06676.

ii. The variance of the amount you win is of 0.1211$².

What is the distribution that models the situation?

Considering you can win with black and yellow balls, the probability of getting two balls off the same color is given by:

p = 2 x 5/10 x 4/9 = 0.4444.

Hence the distribution of the earnings is given by:

  • P(X = 1.1) = 0.4444.
  • P(X = -1) = 0.5556.

What is the mean of a discrete distribution?

The expected value of a discrete distribution is given by the sum of each outcome multiplied by it's respective probability.

Hence:

E(X) = 1.1 x 0.4444 - 1 x 0.5556 = -$0.06676.

The expected value of the amount you win is of -$0.06676.

What is the variance of a discrete distribution?

The expected value of a discrete distribution is given by the sum of the differences squared between each outcome and the mean, multiplied by it's respective probability.

Hence:
V(X) = (1.1 - (-0.06676))² x 0.4444 - (1 - 0.06676)² x 0.5556 = 0.1211$².

The variance of the amount you win is of 0.1211$².

More can be learned about discrete probability distributions at https://brainly.com/question/24802582

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