1. In "Lateness is Passed Down the Schedule", you use the word "task"
to describe the activities. In Fig 1.3, you use the word "story." It
seems you should use the "task" in the figure. "Story" was not
introduced previously. Moreover, since you are talking about
traditional plans in this chapter, consider postponing using "story"
until you get to the agile approach. See comment 3 for a related
issue.

2. In "Multi-tasking," you may want to add a comma beween the "and"
and the "if" in the following sentence:

"We're rarely blocked on more than one task at a time and if
working on three or more concurrent tasks, the context-switching time
becomes a much more tangible cost and burden."

3. Question 1.1 presents "stories." Since (I think) there was no
mention of stories in the chapter (except for Fig 1.3), consider
moving this question to another chapter. That chapter should be one
in which you talk about what stories are, why you should use them, how
they can make activities more independent, and how they can aid agile
planning. Hence, you will have set up the context for question 1.1,
hopefully without having rewritten your User Stories book. If nothing
else, question 1.1 should come after your first official use of the
term "story."

4. Question 1.2 refers to the Central Limit Theorem. Most of your
readers probably understand statistics, but consider having an
appendix that describes the statistics you use in the book. If
nothing else, you may want a footnote that describes the Central Limit
Theorem and points to where the reader could get more information.
Also, is there context for the Central Limit Theorem in the chapter?

Chris