Several psychology students are unprepared for a surprise truelfalse test with 1

Question

Several psychology students are unprepared for a surprise truelfalse test with 17 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 11 correct answers)? Why or why not? = | | (Round to one decimal place as needed ) b. Choose the correct answer below. O A. Yes, because 1 1 is within the range of usual values. O B. No, because 11 is within the range of usual values. ° C. Yes, because 11 is greater than the maximum usual value D. Yes, because 11 is below the minimum usual value.

Explanation / Answer

a. Probability of a correct guess p = Probability of an incorrect guess 1 - p = 0.5.

Number of questions n = 17

= 17 * 0.5 = 8.5.

= (np(1-p))

= (8.5*0.5)

= 4.25

= 2.0616.

b. X = 11

z = (X - ) /

= (11 - 8.5) / 2.0616

= 1.2127.

P(Z >= 1.2127) = 0.1126.

Since 0.1126 > 0.05,

B. No, because 11 is within the range of usual values.

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