Stat134 Spring 2008 Problems.

Learning mathematics and statistics requires practice, the more the better.  You will not get a good grade in this class otherwise.  Don't fool yourself by looking at the answers in the back before you do the problems, work problems through first.  What follows here is a list of suggested problems.

Chapter
Essential Problems
1.3
#5, #7, #9, #11, #13 

Extra Problem:
Use the axioms of probability to prove the formulas given for P(A) when the sample space S is finite and all outcomes are equally likely.

Extra Problem (HARD):
Consider the discrete set { 1/N, 2/N, .... ,1 } (N is any fixed positive integer).  Pick an outcome uniformly at random from this set. For any interval A contained in [0,1], compute the probability that the outcome is in A. 

For A fixed, consider the value of P(A) as N tends to infinity.  Identify the limiting value, which we denote by P(A). 

Show that P(A) satisfies the axioms for a probability as we have defined them in 1.3 with respect to sets A which are mutually disjoint finite unions of subintervals of [0,1].  (In particular, verify the additivity axiom).

Can you identify P(A) with any distribution that has been defined thus far?

1.4A
#2, #6, #8, #12

  1.3 and 1.4A Due Week 2
1.4B
#4, #10
The Monty Hall Problem:

The Gameshow `Lets make a deal'  was popular back in the 70's.  In it a contestant was asked to select one of three doors.  behind each door was a `prize'; Two legit and one a dud (say a years supply of dog food....).  After the selection is made by a contestant, Monty Hall (the host) reveals what was behind one of the remaining doors (not selected by contestant).  Always he revelas a door which contains a legit prize.  Then, he asks the contestant if they would like to switch their selection to the other remaining door.

What should the contestant do?  Is there a strategy which maximizes the frequency with which he or she wins?  Hint:  Try and compute conditional probabilites of winning depending on where the dud prize is.  Hint 2:  THIS IS A FAMOUS PROBLEM.  You could (if you are really stuck) find it online.


1.5
2, 7, 8
1.6
2, 4

1.4B, 1.5, 1.6a Due Week 3
1.6b
6, 7, 8

For each k, give an example of a proability space and events A_1,..., A_k on the space so that

A:  each k-1 grouping is independent
B: The entire collection is not

Hint:  Try to generalize our 2 coin example for k=3
2.1
2, 6, 8, 10, 14

1.6b, 2.1 due Week 4
2.2a
1, 6, 9, 12, .... 15 (for some calculus practice....)
2.2b
16, 17
2.4
2, 4, 6, 8

2.2ab , 2.4 due Week 5
2.5
Evens

Due by Teusday at Exam.
3.1
 4, 5, 10, 17, 20, 22
3.2
10, 14, 16, 20

Due Thurs. March 6
3.3
3, 8, 10, 16, 18, 22, 26, 30

Due Thurs. March 13
3.4
All Even Problems

Due Thurs. March 20
3.5
4, 8, 11, 14, 17, 18
Ch 3 Review (for practice only)
Warmup:
4, 6, 9, 14, 16, 21

Serious:
22, 24, 29, 30, 33


Hard:
31

Hardest:
41
4.1
2, 3, 4, 7, 10, 11

3.5, 4.1 due April 8
4.2
4, 6, 8, 12, 13

4.2 due April 10
4.4
1, 2, 4, 6, 10
4.5
4, 5, 6, 8
4.6
No Longer part of HW

4.4, 4.5 due day of midterm (in principle you may hand them in on thurday April 17 BUT they will be on the exam)
5.1
1, 2, 4, 7, 8
5.2a
2, 6, 11, 13

Due April 24
5.3
2, 3, 4, 6, 8, 11

Due May 1
6.1
4, 8
6.2
2, 4, 6, 7, 8, 17

Due May 8
6.3
2, 4, 8, 10

Due at Final Exam