7. A researcher h as participants choose between three advertisements, She finds

Question

7. A researcher h as participants choose between three advertisements, She finds that 12 prefer Ad A, 22 prefer Ad B, and 18 prefer Ad C. The probability or proportion of participants preferring Ad B is 8. A researcher determines that students study an average of 60 ± 1 5 (M± SD) minutes per week. Assuming these data are normally distributed, what is the z score for students studying 45 minutes per week? 9. A researcher records the following number of birdcalls made during an experimental session with robins: 8.4± 09 (M ± SD). A normally distributed, what is the probability that robins made more than 11 Assuming these data are birdcalls during this experimental session?

Explanation / Answer

7) P(preferring Ad B) = 22/(12 + 22 + 18) = 0.423

8) Z-score = (X - M)/SD

                  = (45 - 60)/15

                  = -1

9) P(X > 11)

= P((X - M)/SD > (11 - M)/SD

= P(Z > (11 - 8.4)/0.9)

= P(Z > 2.89)

= 1 - P(Z < 2.89)

= 1 - 0.9981

= 0.0019

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