Q: 20 Several psychology students are unprepared for a surprise true/false test

Question

Q: 20

Several psychology students are unprepared for a surprise true/false test with 15 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 10 correct answers)? Why or why not? a. mu = b. Choose the correct answer below. A. No, because 10 is within the range of usual values. B. Yes, because 10 is greater than the maximum usual value. C. Yes, because 10 is below the minimum usual value. D. Yes, because 10 is within the range of usual values.

Explanation / Answer

P(guessing correct answer) = 0.5

n = 15

a) = n * p = 15 * 0.5 = 7.5 = 8

= sqrt(n * p * (1 - p)) = sqrt(15 * 0.5 * (1 - 0.5)) = 1.9

b) Z = (X - ) /

Z score for 10 = (10 - 7.5) / 1.9 = 1.3

Since the Z value is less than 2, 10 ps within the range of usuals value

Oprion-A)

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