Stephanie wonders whether college textbooks change in price as students advance in their academic work.She finds some national data on college textbooks that indicates the average price of a text is $96 with a standard deviation of $31.She decides to collect the prices of 30 textbooks that are required for senior-level courses at her university.She finds the average cost to be $89.What is the percentile rank of Stephanie's collection of books? (Round z score to two decimal places.)
A) 8.71
B) 10.75
C) 39.25
D) 41.29

Question

Quizplus · Accepted Answer

The z-score is calculated as (89 - 96) / (31/√30) = -1.25. Using the z-table, a z-score of -1.25 corresponds to a percentile rank of approximately 10.75.

Stephanie Wonders Whether College Textbooks Change in Price as Students