Question

Several psychology students are unprepared for a surprise trueMalse test with 17 questions, and all of their answers are quesses a. Find the mean and standard deviation for the number of correct answers for such students. b. Would il be unusual for a student to pass by guessing (which requires geting at least 14 correct answers)? Why or why not? (Do not round) a. (Round to one decimal place as needed.) b. Choose the correct answer below O A. No. O B. Yes, because 14 is within the range of usual values. O C. Yes, because 14 is greater than the maximum usual value. O D. Yes, because 14 is below the minimum usual value. , because 14 is within the range of usual values.

Answer 1

Sample size, n = 17

P(correct answer), p = 0.5

a) Mean, $\small \mu$ = np

= 17 x 0.5

= 8.5

Standard deviation, $\small \sigma$ =

npq

=

V17 x 0.5 x 0.5)

= 2.1

b) A value is considered unusual if it is either more than 2 standard deviations below mean or more than 2 standard deviations above mean.

Range of usual values = 8.5 $\small \pm$ 2x2.1

= 4.3 to 12.7

C. Yes, because 14 is greater than the maximum usual value.