C adding a number to itself
Considering the probabilities of getting each question right, his expected score for the test is 90.8.
<h3>How to find Joe's expected score?</h3>
Joe's expected score is given by the sum of the expected score for each question.
We have that:
- He is sure of 12 answers, hence for each he expects 6 points.
- He randomly guesses on 9 problems, hence he is expected to have a 1/5 probability of earning 6 on them.
- For the other 4 problems, he has a 1/3 probability of earning 6 on them, as he will guess from 3 options as he eliminated 2.
Hence his expected score is given by:
E(X) = 12 x 6 + 9 x 1/5 x 6 + 4 x 1/3 x 6 = 90.8.
More can be learned about the expected score of a distribution at brainly.com/question/13617733
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Answer:
it's
Step-by-step explanation:
(2f+2)(2f-2)
(2f^2-2^2)
