Math 213 F1
Midterm Exam 2 Information
Basic Information
 Exam date, time, and location:
The exam will be given during the regular class time, Friday,
10/15/2010, 2:00  2:50, in the usual room, 147 Altgeld.
 Exam rules: No calculators, closed books/notes, and, of
course, no cheating.
 Missed Exam policy. I don't give makeup exams, but
if you miss the exam with a valid
excuse (e.g., illness), the exam will be counted as "excused". (See the
Course Information Sheet for an
explanation of an "excused" exam score.)
The absence must be documented by an "absence letter" from the Dean's
Office at 300 Student Services Building, 610 East John St., phone
3330050.
 Grading. The exam will
account for approximately 1/6 of the total points to be earned in this class.
See the Course Information Sheet for the complete
grading policy. After the exam has been graded and the scores entered
into the grading system, you can view your scores via
this link.
 Open House hours: Tuesdays, Wednesdays, and Thursdays,
5 pm, in 159 Altgeld (or an adjacent room in case 159 is taken).
I will stay as long as someone is there. Take
advantage of this opportunity!
I'm happy to answer questions by email
(ajh@illinois.edu), but keep in mind that email is best suited for quick,
nontechnical questions (e.g., do we have to know XYZ?); for technical
questions that require a lengthy explanation it's better to ask in
person.
Syllabus
The exam will on Sections 5.1  5.5 and 6.1  6.3, i.e., the material covered
in class since the last midterm and through Monday, Oct. 11.
Below is a more detailed syllabus. As a general rule, anything that is not
explicitly excluded from the exam in the syllabus below
is fair game for the exam. If you are not sure, ask!
 Basics of Counting (5.1)
Product and sum rules. Simple inclusionexclusion.
Examples 18, 10, 11, 12, 1518.
Skip: Tree diagrams (p. 343).
 The Pigeonhole Principle (5.2)
Basic version (k+1 objects, k pigeonholes) and generalized version (N objects, k
pigeonholes). Examples 18.
Skip: Final part, "Elegant applications".
 Combinations and Permutations (5.3):
Examples 115.
 Binomial Coefficients (5.4):
Binomial theorem (you need not know the proof).
Examples 14. Skip: Final part, "Some other identities ...".
 Generalized Combinations and Permutations (5.5):
Permutations with repetition. Combinations with repetition. Donut type
problems. Counting integer solutions.
Skip: Final part, "Distributing objects into boxes".
 Basic Probability (6.1):
Equally likely outcome model. Examples 18.
Skip: Example 10 (Monty Hall problem). (This is a famous and interesting
problem. Read it if you are interested, but it's not going to be on the
exam.)

Probability Theory (6.2):
General model with finitely many outcomes, and a general (not necessarily
uniform) probability assignment.
Success/failure (Bernoulli) trials, and the binomial distribution.
Conditional probability. Independence.
Examples 19, 13, 14.
Skip: Random variables (p. 408409), MonteCarlo Algorithms and Probabilistic
Method (p. 411414).

Bayes' Theorem (6.3):
Bayes' Theorem, basic version (Theorem 1)
Examples 13. (Skip Theorem 2 and the last example, Example 4.)
Other information
Exam format:
The exam will have 6  9 problems, usually with multiple parts; some may be
in true/false, or multiple choice format.
For combinatorial problems, which
make up the bulk of this exam, the same rules as for the homework apply:
 Leave all answers in "raw", unevaluated form, e.g., involving factorials
and binomial coefficients.

Indicate briefly how you arrived at each component in your formula (e.g., by
a "bubbledin" phrase like "pick 2 days out of 366").

All problems have a simple answer consisting of at most two or three terms of
simple shape, if approached in the right way. This simple answer is the one
you are expected to derive. A messy sum will not count. (Example: the
probability that there are at least 2 sixes in 100 coin tosses can easily be
given in very simple form, using the complement rule, and this is the
expected solution; by contrast, a sum of 99 binomial probabilities from k=2
to k=100 would not qualify as a simple answer, and would not earn credit.)

All problems are doable with minimal amount of calculations, using standard
techniques, of the type illustrated in the class examples and homework
problems. If you get entangled in a lengthy calculation, you are on the
wrong track, and it's better to move on to another problem.
Continuing would be counterproductive. You won't get credit for answers
arrived at by brute force counting.

Note on poker problems: You need not know any special poker terms
("full house", etc.); all you need to know is the basic composition of a deck
of cards (52 cards total, split into 4 suits of 13 cards each).

Note on word counting problems: Assume (as in the hw problems) that there are
26 letters. Unless otherwise indicated, we are only counting upper case words
(again just like in the class examples and hw problems).

Note on calendar day/month problems: Basic assumptions, such as the number of
days per year (or per month) to work with, will be given in the problem.
(In the text the usual assumptions are 366 days per year and 30 days per
month; in any case, in the exam, this will be specified.)
Past Math 213 exams.
Click on this link for some old Math 213 exams. This should give you some
idea of the length and difficulty level of the exam. In terms of material
covered, however, they are not representative since the old exams were based
on a different syllabus, so it would not make much sense to use these exams
to prepare for our exams.
Tips on preparing for the exam:

Start studying early. Try to find someone, or a group, to study with.

Start your prepration with your class notes, make sure you understand the
basic concepts and techniques, rework the class examples. The class examples
were carefully selected to illustrate the different types of combinatorial
and probability problems at a level appropriate for this class.

For additional practice, study the
corresponding section in the text, and rework the examples there using the
above syllabus as a guide. Note that the examples in the text vary widely
in difficulty. Many are very easy warmup problems, but a few are quite
difficult, well above exam level. The examples listed in the above syllabus
are all of the "doable" kind.

Redo the homework problems (both the graded
and nongraded hw), especially those you got wrong, or you weren't sure
about.

Lastly, take advantage of the Open House (see above).
Back to the Math 213 Homepage
Last modified: Mon 11 Oct 2010 04:11:01 PM CDT
A.J. Hildebrand