Answer and explanation:
Keira could get or look up an electronic copy of the book online. Once she has an electronic copy(pdf for instance) of the book, she can count number of e's in her book using the PDF reader or any software extension(good number of tools online) that would do just that.
Factors for Keira to consider:
How many lines and words are there on average per page; how many words are there per line?
How many e's are there manually counting for at least 5 pages.
Problems Keira might have in collecting data:
If book is physical and not an electronic copy, Keira may have to go through a tedious task of counting manually. She could make a rough estimation based on a few pages counted but she would need more accurate figures which requires the tedious task of counting e 's manually