PSY 300 USC Beaufort Statistics for the Behavioral Sciences Worksheet

Psy 300 – Statistics for the Behavioral Sciences
Homework 2
A distribution of scores is normal with M = 45 and s = 8. Find the z-scores that correspond to the following raw scores:
1. X = 32
2. X = 47
z=
z=
For the same distribution, find the raw scores that correspond to the following z-scores:
3. z = 2.6
4. z = -1.4
X=
X=
5. Stan and Lia both took a History test in different classes. Stan’s score was 82 with a class distribution of M=80 and s=6.
Lia scored a 78 with a class distribution of M=76 and s=4. Using z-scores, explain why Lia did “better” on the test even
though her raw score was lower.
Find the following:
6. p(z < 1.9) = 7. p(z < -2.1) = 8. p(z > 1.3) =
9. p(z > -.9) =
Given a normal distribution with M = 200 and s = 20, find the following:
10. The z-score equivalent for a raw score of 240 =
11. p(X > 240) =
12. The z-score equivalent for a raw score of 165 =
13. p(X > 165) =
14. The z-score that separates the top 10% of scores =
15. The raw score that separates the top 10% of scores =
16. The z-score that separates the top 75% of scores =
17. The raw score separates the top 75% of scores =
18. The z-score separates the bottom 40% of scores =
19. The raw score that separates the bottom 40% of scores =
20. The z-score equivalent for a raw score of 172 =
21. The percentile for a raw score of 172 =
22. The z-score equivalent for the 85th percentile =
23. The raw score equivalent for the 85th percentile =
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
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A researcher hypothesizes that this season’s football players (n=25) have higher aggression levels than last season’s
players. On an aggression survey, the average score for this season is 35.7 with s= 5.1. Last season, the mean aggression
score on the survey was 30. Find the following, using =.05:
24. HO:
25. H1:
26. df =
27. tcrit =
28. sM =
29. M- =
30. tobt =
31. Decision regarding HO:
32. Interpretation in APA format:
33. r2 =
Students from a college emphasizing “green” living were hypothesized to differ in conservation activity participation
compared to students from other colleges. A sample of 6 students from the “green” college participated in conservation
activities an average of 15 times over the past year (s=5.7). The overall average among college students is 12. Find the
following, using =.05:
34. HO:
35. H1:
36. df =
37. tcrit =
38. sM =
39. M- =
40. tobt =
41. Decision regarding HO:
42. Interpretation in APA format:
43. d =
Extra credit (1 point): In a normal distribution, what percentile corresponds to the median?