Exercise 21 Page 717

Percentiles separate data sets into 100 equal parts. The percentile rank of a data value is the percentage of data values that are less than or equal to that value. Let's find the percentile rank of a data value 1. Therefore, we have to find how many values are less than or equal to 1. Data set 1, 1, 1, 1, 1, 1, 2, 3, 5, 8, 13 21, 34, 55, 89, 89, 89, 89, 89, 89 Now, we know that 6 values out of the 20 total values are less than or equal to 1. 6/20 = 0.3 = 30 % The percentile rank of a score of 1 is 30.