Statistics for the Behavioral Sciences by Frederick J. Gravetter, Larry B. Wallnau ISBN 10: 1305504917 ISBN 13: 9781305504912

PROBLEMS 65
19. The following table shows four rows from a frequency
distribution table for a sample of n = 25 scores. Use
interpolation to find the percentiles and percentile
ranks requested:
X f cf c%
8 3 18 72
7 6 15 60
6 5 9 36
5 2 4 16
a. What is the percentile rank for X = 6?
b. What is the percentile rank for X = 7?
c. What is the 20th percentile?
d. What is the 66th percentile?
20. The following table shows four rows from a frequency
distribution table for a sample of n = 50 scores. Use
interpolation to find the percentiles and percentile
ranks requested:
X f cf c%
15 5 32 64
14 8 27 54
13 6 19 38
12 4 13 26
a. What is the percentile rank for X = 13?
b. What is the percentile rank for X = 15?
c. What is the 50 th percentile?
d. What is the 60 th percentile?
21. The following table shows four rows from a frequency
distribution table for a sample of n = 50 scores. Use
interpolation to find the percentiles and percentile
ranks requested:
X f cf c%
15–19 3 50 100
10–14 6 47 94
5–9 8 41 82
0–4 18 33 66
a. What is the percentile rank for X = 17?
b. What is the percentile rank for X = 6?
c. What is the 70th percentile?
d. What is the 90th percentile?
22. The following table shows four rows from a frequency
distribution table for a sample of n = 20 scores. Use
interpolation to find the percentiles and percentile
ranks requested:
X f Cf C%
40–49 4 20 100
30–39 7 16 80
20–29 4 9 45
10–19 3 5 25
a. Find the 30th percentile.
b. Find the 52nd percentile.
c. What is the percentile rank for X = 46?
d. What is the percentile rank for X = 21?
23. Construct a stem and leaf display for the data in problem
5 using one stem for the scores in the 50s, one for
scores in the 40s, and so on.
24. A set of scores has been organized into the following
stem and leaf display. For this set of scores:
a. How many scores are in the 70s?
b. Identify the individual scores in the 70s.
c. How many scores are in the 40s?
d. Identify the individual scores in the 40s.
4 8
5 421
6 3824
7 592374
8 24316
9 275
25. Use a stem and leaf display to organize the following
distribution of scores. Use six stems with each stem
corresponding to a 10-point interval.
Scores:
36, 47, 14, 19, 65
52, 47, 42, 11, 25
28, 39, 32, 34, 58
57, 22, 49, 22, 16
33, 37, 23, 55, 44