A multiple-choice test consists of 30 questions. Each question has five possible

Question

A multiple-choice test consists of 30 questions. Each question has five possible responses, of which only one is the correct answer. Each correct answer is worth 5 points and each incorrect answer loses 1 point (a negative score). A question that is left unanswered is worth 0 points. A student who is totally unprepared takes the test. She answers each question by selecting one of the five answers at random, independently of the answers chosen for other questions. Find her expected total score on the test. A. 12 B. 6 C. 0 D. -3

Explanation / Answer

P(correct answer) = P(5 points) = 1/5 = 0.2

P(wrong answer) = P(-1 point) = 4/5 = 0.8

Expected score = (5 * 0.2 - 1 * 0.8) * 30 = 6

So, the correct option is Option-B) 6

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