One way to measure a person’s reading fluency is to have them read an unpracticed passage for one minute. The researcher then counts the number of words read correctly, which is called words correct per minute (WCPM). The WCPMs for eighth-graders are approximately normally distributed with mean 151 words and standard deviation 45 words (Source: Oral Reading Fluency Norms: A Valuable Assessment Tool for Reading Teachers, Hasbrouck, Jan, and Tindal, Gerald A.).
a. Find the 50th percentile for the eighth-grader WCPM distribution.
b. The authors of the article cited in the opening paragraph “recommend that a [WCPM] score falling within 10 words above or below the 50 percentile should be interpreted as within the normal, expected, and appropriate range.” Find the percentage of eighth-graders’ WCPMs that fall in the normal, expected, and appropriate range.
c. Assume that readers who do not score in the range described in part (b) are either slow readers or fast readers. On the basis of your result in part (b), what percentage of eighth-graders are slow readers? Fast readers? Do these percentages seem reasonable? Explain.
d. Describe an interval of WCPM scores that contains the middle 80% of the scores.