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T 1/7/14
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No additional HW is due.
Prepare for another quiz similar to yesterday or, more likely, a written
quiz. All notation, terminology, and general techniques from the first
semester are fair game.
Sample questions:
1. E(X), where X denotes a
binomial random variable, equals what two
other expressions that we learned?
Answer: 
2. All geometric distributions have what shape?
Answer: Skew
right.
3. Is the binomial distribution with n
= 20, N = 130, and p > 0.95 approximately normal?
Answer:
Goodness, no. Not only is the sample size more than 10% of the population
size, which ruins the assumption of approximately independent trials, but nq < 1. We
need both np
and nq to
be at least 10, as a rule of thumb, in order to apply the normal
approximation.
4. The LSRL giving bubblegum stretchiness (y), in cm, as a function of force applied (x), in newtons, is  State the slope and
interpret it in context.
Answer: The
slope is b1 = 0.218. For
each increase of 1 newton of force, the LSRL model
predicts an increase of 0.218 cm in the bubblegum’s
stretchiness. [Or, you could say, “On average, each 1-newton increase in
force is associated with a bubblegum stretchiness increase of 0.218 cm.”]
Note: One thing you must not do is
to imply that the bubblegum stretches an additional 0.218 cm for each
additional newton of force—that’s false, since in
any real-world scatterplot, sometimes the increase
matches the overall LSRL slope, and sometimes it doesn’t, but mostly it
doesn’t. The words “on average” or “the model predicts . . .” must be present
in order for you to earn full credit.
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Th
1/9/14
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HW due: On a clean sheet of
paper, log at least 35 minutes’ worth of AP review problems, either from the
link at the end of the 1/13 calendar entry or from an AP review book (or
both, if you wish). For each problem, write the page number and problem
number before starting your writeup. You do not
need to rewrite the questions.
Important: You must go back at the
end and grade your work in a different color. Make a checkmark for each
question you answered correctly and an “X” (with corrections) for each
question you answered incorrectly.
For tonight, do either all multiple-choice problems or all free-response
problems, your choice. For items taken from the website, record the year of
the exam and the form type as well—“regular” or “Form B.”
In class: Review.
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F 1/10/14
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HW due: Same as yesterday’s
assignment, except that if you did multiple-choice problems for yesterday, do
free-response for today, and if you did free-response problems for yesterday,
do multiple-choice for today.
In class: Review.
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M 1/13/14
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Midterm Exam, MH-108, 8:00 a.m.–10:00 a.m.
Bring several sharpened pencils, spare batteries, and at least one calculator
from the TI-83/84 family. The format will be as follows:
Part I: Multiple choice (20 questions, 45 minutes)
Part II: Free response (2 questions, a “short” and a “long,” total of 38
minutes)
This will be similar to the real AP exam, except with shorter segments. To
study, you should work practice problems from an AP review book and from the College
Board AP Statistics website.
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