Textbook authors must be careful that the reading level of their book is appropriate for the target audience. Some methods of assessing reading level require estimating the average word length. We've randomly chosen 20 words from a randomly selected page in Intro Stats and counted the number of letters in each word:

5,5,2,11,1,5,3,8,5,4,7,2,9,4,8,10,4,5,6,6,

Suppose the editor was hoping that the book would have a mean word length of 6.5 letters. Does this sample indicate that the authors failed to meet this goal? State and test an appropriate hypothesis and state your conclusion.