We want to get the expected value for the given experiment, we will see that it is equal to -1/6 points, so the correct option is "negative one-sixth"
For an experiment with events {x₁, x₂, ..., xₙ}, each one with probability {p₁, p₂, ..., pₙ}, the expected value is given by:
EV = x₁*p₁ + ... + xₙ*pₙ
Here we have two events:
- x₁ = she gets 9 points.
- x₂ = she loses 2 points.
Let's find the probabilities of each one of these.
She gets 9 points if the sum of the two dice is equal to 8 or 12.
Each dice has 6 outcomes.
Then a combination of two dice has a total of 6*6 = 36 outcomes.
The outcomes that add to 8 or 12 are:
dice 1 dice 2 sum
2 6 8
3 5 8
4 4 8
5 6 8
6 2 8
6 6 12
So 6 out of the 36 outcomes, then the probability of this event is:
p₁ = 6/36 = 1/6
And the other event is for all the other outcomes, so the probability is just:
p₂ = 5/6
Then the expected value is:
EV = (+ 9 points)*(1/6) + (-2 points)*(5/6) = -1/6 points.
So the correct option is negative one-sixth.
If you want to learn more about expected value, you can read:
brainly.com/question/22097128
