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

SECTION 2.4 | Percentiles, Percentile Ranks, and Interpolation 49
LEARNING CHECK
1. The seminar rooms in the library are identified by letters (A, B, C, and so on). A
professor records the number of classes held in each room during the fall semester.
If these values are presented in a frequency distribution graph, what kind of graph
would be appropriate?
a. a histogram
b. a polygon
c. a histogram or a polygon
d. a bar graph
2. A group of quiz scores ranging from 4–9 are shown in a histogram. If the bars in
the histogram gradually increase in height from left to right, what can you conclude
about the set of quiz scores?
a. There are more high scores than there are low scores.
b. There are more low scores than there are high scores.
c. The height of the bars always increases as the scores increase.
d. None of the above
3. If a frequency distribution graph is drawn as a smooth curve, it is probably showing
a ______ distribution.
a. sample
b. population
c. skewed
d. symmetrical
4. A set of scores is presented in a frequency distribution histogram. If the histogram
shows a series of bars that tend to decrease in height from left to right, then what is
the shape of the distribution?
a. symmetrical
b. positively skewed
c. negatively skewed
d. normal
ANSWERS
1. D, 2. A, 3. B, 4. B
2.4 Percentiles, Percentile Ranks, and Interpolation
LEARNING OBJECTIVES
8. Define percentiles and percentile ranks.
9. Determine percentiles and percentile ranks for values corresponding to real limits in
a frequency distribution table.
10. Estimate percentiles and percentile ranks using interpolation for values that do not
correspond to real limits in a frequency distribution table.
Although the primary purpose of a frequency distribution is to provide a description
of an entire set of scores, it also can be used to describe the position of an individual