Time Limit: 03:00:00 est: Final Exam This Test: 21 is Question: 1 pt 100121 (1o

Question

Time Limit: 03:00:00 est: Final Exam This Test: 21 is Question: 1 pt 100121 (1o complete) Several psychology students are unprepared for a surprise trueffalse test with 18 questions, and all of their answers are guesses. a. Find the mean and standard deviation for the number of correct answers for such students b. Would it be unusual for a student to pass by guessing (which requires getting at least 16 correct answers)? Why or why not? (Round to one decimal place as needed ) b. Choose the correct answer below O A. No, because 16 is within the range of usual values O B. Yes, because 16 is within the range of usual values. ° C. Yes, because 16 is below the minimum usual value. D. Yes, because 16 is greater than the maximum usual value ss Click to select your answer(s). tests and quizzes can be taken for practice or to build your study plan. Sample tests and quizzes do not affect your grade

Explanation / Answer

p = 0.5

n = 18

a) mean = n * p = 18 * 0.5 = 9

standard deviation = sqrt(n * p * (1-p)) = sqrt(18 * 0.5 * (1 - 0.5)) = 2.1

b) maximum ususal values = mean + 2 * sd = 9 + 2 * 2.1 = 13.2

Since 16 is greater than 13.2, passing is unusual.

Option-D)

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