Problema Solution
each question on a multiple-choice exam has five choices. One of the choices is the correct answer, worth 5 points. There are two other choices that are wrong but still carry partial credit of 2 points each. The other two choices are worth zero 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 40 questions, what is his or her expected score?
Answer provided by our tutors
the expected value of his or her score for a problem is:
E1 = (1/5)*5 + (1/5)*2 + (1/5)*2 + (1/5)*0 + (1/5)*0
E1 = 1.8 points.
if the exam has 40 questions, his or her expected score is:
E = 40*E1
E = 40*1.8
E = 72 points.