Home Page for Math 361

This is the home page for Math 361, "Introduction to Probability", Section D1. This class meets for the Fall 1999 semester on MWF 11 at 154 Henry. My intention is to provide, at the very least, an archive for all of the handouts in the course and a guide to the semester, class-by-class.

I will be available in my office, 243 Illini Hall, from 10:30 to 12:30 and 2:00 to 4:00 on Sat. Dec. 11, and will be answering my email and monitoring the newsgroups through Thursday night, in advance of our final at 8:00 am on Fri. Dec. 17.

Last revised Dec. 10, 1999

Class Diary

For reasons of space, material from before the second test has been moved.
M 11/1 -- Second Hour Exam


W 11/3 -- Went over the exam for about a third of the class, and spent the rest talking about changes of variable from the point of view of ``first principles". That is, I find that it's almost always easier to compute P(g(X) < y) by looking at it directly, rather than by remembering a formula. The most complicated example was the distribution of X^2, when X is uniform on [-2,3]. I also passed out HW9 .


F 11/5 -- Discussion of the cumulative distribution function, and also how to think about the maximum and minumum of a set of independent random variables, and the formula that, if X is a non-negative random variable with finite expectation, then E(X) is the integral of P(X > x) as X runs from 0 to oo.


M 11/8 -- I passed out HW9 solutions , and talked about several of the problems. The solution given there for problem 4 has several errors. I then began with § 5 from the book.


W 11/10 -- I passed out more on HW 9, which includes a corrected solution to problem 4. More discussion of §5.1,2. At the end, I passed out HW10 .


F 11/12 -- Some review of what we had done in Chapter 5 to date, some answering of questions about HW10, some discussion of the "Parental Notification" issue. A hodge-podge, but those who were there felt it was worthwhile.


M 11/15 -- A bit more than half the class was spent going over the HW10 solutions , and the rest was devoted to a proof that linear combinations of independent normally distributed random variables are also normally distributed. At the end, I passed out HW11 .


W 11/17 -- Another 20 minutes talking about HW10, with a review of integration in the plane which evidently should have been done sooner. More on the sum of two independent normal random variables, and some related word problems worked in detail. For those of you who plan to turn in the homework on Friday, the Gamma distribution is discussed in § 4.2 and will be covered in class on Friday.


F 11/19 -- An attempt to finish up § 4, 5. Discussion of the Gamma distribution and more examples, based on class request. Presentation of book problem 5-4-11.


M 11/22 -- More review. Several homework problems gone over, and an explanation of the significance of the Gamma(1/2,lambda) distribution: if X is standard normal, then X^2 is Gamma(1/2,1/2). Passed out: HW11 solutions and HW12 .

M 11/29 -- A review of Homework 11, plus coverage of § 6.1, 6.2. This material is largely intuitive and much has already been covered in class.


W 12/1 -- Some hints for Homework 12, plus coverage of § 6.3. Formulas were presented which allow one to avoid double integrals in compution the distribution of X + Y, etc. There was some discussion of whether these were easier or harder.


F 12/3 -- Passed out: HW12 solutions . I talked about HW 12 and some of § 6.4 about correlation and covariance. Only 10 of 23 in class when the bell rang. I said I needed 17 to distribute the ICES forms and get a meaningful return. The 17th person walked in around 11:20, and the forms went out at 11:40.


M 12/6 -- Review for the Third Exam


W 12/8 -- Third Hour Exam.


F 12/10 -- Third exam returned; last day of instruction.


S 12/11 -- Reading Day: Office Hours 10:30 am -> 12:30 pm and 2:00 pm -> 4:00 pm

F 12/17 -- Final Exam, 8:00 -> 11:00 am.

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