i need help on expected values...

Question

Each question on a multiple-choice exam has five choices. One of the choices is the correct answer, worth 4 points, another choice is wrong but still carries partial credit of 1 point, and the other three choices are worth 0 points.

If a student picks answers at random, what is the expected value of his or her score for a problem?

If the exam has 20 questions, what is his or her expected score

Answer 1

answer worth prob

correct 4 0.2

partial 1 0.2

wrong 0 0.6

expected = 4 * 02 + 1 * 0.2 + 0 = 1 per question

20 questions, expected score 20.