Class Updates: WeBWorK, Exam #3, my black eye

A few important items:

  1. Yes, I was indeed in a bike accident today.  I was lucky and walked away with a few scrapes, 3 stitches and a black eye.  You can check out the damage on Thursday.  Here is card that my almost-4-year-old daughter made for me – she says it is a picture of “funny smiling people, to make you laugh,” but I swear the one on the right looks just like me sailing through the air over my bicycle.
  2. The deadline for WeBWorK #9 has been extended to this Thursday, April 18th, at midnight.
  3. WeBWorK #10 is ON HOLD for now — the deadline and problems may be changed.  Don’t work on it for now.  I’ll give you an update on Thursday.
  4. The third exam, scheduled to take place next Tuesday, is postponed by one class day.  The new date for the third exam is next Thursday, April 25.  A review sheet is available on the Handouts page, and will be distributed in class this Thursday.

Take care, and be safe,
– Mr. Reitz


UPDATE MONDAY 4/15/13:  I found that for some (but not all) students, problem #8 was also having similar trouble.  It is fixed, as of 8:23pm.

Hi everyone,

It was pointed out in class today that some of the problems in WeBWorK #9 were being marked incorrect, even if you follow exactly the steps described in class.  I have tracked down the source of the error, and updated a number of problems in the assignment — they should all be working properly now.

Unless further problems are discovered, the due date for WeBWorK #9 will remain next Tuesday, April 16, at midnight.

If you believe that a problem is still not working correctly (that is, you think your answer is right but WeBWorK is not accepting it) please send me an email and let me know.

– Mr. Reitz

ps.  If you’re interested (GEEK ALERT), the errors arose because we use a table to find z / probability, and the table is limited in the number of decimals it will provide.  Solving these problems on a calculator gives more decimals of accuracy (but requires a more specialized calculator, such as a graphing calculator)

OpenLab #9: Reflecting on the class so far

Every college class is planned with certain goals in mind – to convey ideas, to encourage certain kinds of thinking, to provide opportunities for learning, for exploration, for practice.  A typical plan consists of a mix of different activities, both in and out of class, and hopefully each activity contributes to achieving the goals of the class.  In this assignment, I am going to ask you to think about some of the different things we do for this class and reflect on their effectiveness.

Some of the activities that make up this class are listed below.  This list is not comprehensive (it may be missing things!), and includes both in-class and out-of-class activities.

Partial list of class activities:

  • lectures
  • webwork assignments
  • openlab assignments
  • exams
  • answering questions at the board (often at the start of class)
  • doing examples on the board (often during the course of a lecture)
  • asking/answering questions on the OpenLab
  • working on problems individually during class
  • group work during class
  • asking/answering questions by email
  • office hours

Assignment (Due Thursday, April 18th, 2:30pm).  Respond to at least two of the following questions (1 or 2 sentences each).  Feel free to discuss activities that are not listed above, if you wish.

  1. What activities have been most useful to you in preparing for exams? Why?
  2. What activities have been most useful to you in making connections between the class material and other areas of your life? Why?
  3. What activities have been most useful in building community in our class (creating a comfortable atmosphere, getting to know your fellow students, building trust)? Why?
  4. Are there any activities that you would like to spend more time on (this includes activities that are not on the list, but you think should be included)? Explain?

OpenLab #8: Take a break, read a book

You have no OpenLab assignment this weekend.  If you wish, you can earn a little extra credit by responding to the following.

Extra Credit (due Thursday, April 11, 2:30pm)  Hey, what are you reading?  Tell me one book you like, and very briefly why you like it.  It can be something you read recently, or an all-time favorite.  It can be serious or fun, something you read to pass the time, or in school, or to improve yourself, or for some other reason.  Any kind of book is fine — literature, science fiction, romance, nonfiction, graphic novels, whatever.  Be sure to include the author and title, and a link if possible.

I just finished reading Ready Player One by Ernest Cline.  It was fun and fast-paced, just the thing for passing the time on the subway.  I liked the gaming theme,  the dystopian future sci-fi setting, and the unending references to 1980’s culture (that’s when I was in high school).  Fun!

OpenLab #7: Pick a topic (or three)

In the second half of the semester, we’ll be working on creating an annotated study guide for use in preparing for the final. Everyone will be responsible for creating a guide explaining how to do one type of problem.

Assignment (Due Thursday, April 4, 2:30pm). The list below gives an overview of topics/types of problems covered in the class.  In this assignment, you should choose THREE of the following topics that you think are interesting or might like to work on.  One or more of your choices must be from the second half of the class (items 10-18, things we have not studied yet).  Don’t be afraid to choose a topic you don’t know – you will have opportunity to learn, ask questions, and get help along the way!  Respond to this post, including your top three choices (give both the number and name of your choice, for example “my first choice is: #5, probability and counting”).

  1. Frequency distributions (sec 2.1). tallying data, classes, relative frequencies and percentages, histograms
  2. Measures of central tendency (sec 2.3). mean, median, mode
  3. Measures of variation (sec 2.4). range, variance, standard deviation
  4. Representing data visually (sec 2.2, 2.5).  stem-and-leaf plots, quartiles, box-and-whiskers plots
  5. Probability and counting (sec 3.1, 3.4). combinations, permutations, sample space, events, probabilities
  6. Combining probabilities (sec 3.2, 3.3). multiplication rule “and”, addition rule “or”, mutually exclusive events
  7. Independent events (sec 3.2).  conditional probability, given, independent
  8. Discrete probability distributions (sec 4.1).  mean, standard deviation, probability distributions based on frequency, based on tree diagram
  9. Binomial distributions (sec 4.2).  trials, success, failure, binomial formula, finding probabilities in binomial distributions
  10. The Normal Distribution (sec 5.1, 5.2, 5.3).  z score, finding probabilities, finding values
  11. Normal Approximations to Binomial Distributions (sec 5.5). solving binomial problems using the normal distribution, continuity correction
  12. Sample Mean problems (sec 5.4) finding probabilities involving the sample mean
  13. Hypothesis Testing for the Mean (Large Samples) (sec 7.2), null hypothesis, alternative hypothesis, level of significance, rejection region, critical value, z-test
  14. Hypothesis Testing for the Mean (Small Samples) (sec 7.3), null hypothesis, alternative hypothesis, rejection region, critical value, degrees of freedom, t-test
  15. Correlation (sec 9.1), positive and negative correlation, correlation coefficient
  16. Linear Regression (sec 9.2), find equation of the line of best fit/regression line, use it to predict values
  17. Goodness-of-Fit Test (sec 10.1), multinomial experiments, chi-square test
  18. Independence (sec 10.2), chi-square test for independence

OpenLab #6: Get caught up!

As you know, your second exam will take place next Thursday, March 21.    I know you have a lot to work on this weekend, including WeBWorK assignment #6 and the Exam 2 Review Sheet, so we will NOT have an OpenLab assignment this week.  As you are working, if you have questions about WeBWorK, the review sheet, or anything else, I strongly encourage you to post them on the discussion board – either under the existing thread or by creating a new topic.

You can still earn extra credit this week by answering another students’ question on the discussion board.

Best of luck with your studying,
Mr. Reitz

OpenLab #5: Probability in the wild

UPDATE 3/12/13:  There have been some great, and very creative, responses so far – thanks.  Translating a “real-world” percentage into an experiment, and determining the possible outcomes, is a significant challenge!  In many cases I’ve asked a question or made a suggestion — if you respond to my comment appropriately, I’ll give you extra credit for this assignment.  Here are some tips, based on what I’ve seen so far:

  • The Experiment should describe a process that could result in one of several outcomes. 
  • The Outcomes  describe the different possible things that could happen.  There should always be more than one outcome.  Often, news articles will focus on something that already happened (as if the experiment already took place), and so we may already know what outcome was obtained in that particular case, and it’s easy to think of this as “THE outcome” — but there is always something else that could have happened, and might happen if the experiment were repeated. Don’t forget this ‘other outcome’.
  • If your example began with a percentage, this will almost always be the probability that one of the outcomes will happen.  Take a look at your experiment/outcomes — does this fit?

Probability is an idea that shows up very often in the world outside our math classroom.  It occurs whenever a chance of something happening is described, often as a percentage (“a 90% chance of rain”), but sometimes in other forms (“a 9 out of 10 chance”).  However, it is not always simple to see how the basic setup described in class applies to one of these situations — that is, to think of probability in terms of an experiment, with various outcomes.

Recall that an experiment is a process which, when carried out, results in just one of several possible outcomes.  The outcomes are simply the different results that can occur.

Here are some examples from the news:

Example 1:

According to, there is a 10% chance of rain on Thursday, March 14 (at least, this is the percent reported on Wednesday, March 6).

The experiment: we wait and see what the weather is like on Wednesday, March 6.
Outcomes: it rains, it doesn’t rain.

Example 2:

“Spanish researchers have completed the first human trial of a new vaccine against HIV. It has been successful in 90% of the HIV-free volunteers during phase I testing. This vaccine brings great hope to eradicate this plague forever.”

The experiment:  HIV-negative people are given the vaccine, and then are tested to see if they can contract HIV when exposed.
Outcomes: They do not contract HIV (the vaccine was  successful), or they do contract HIV (the vaccine was unsuccessful).

Assignment (Due Thursday, March 14):  Find an example of probability in the news.  Reply to this post including the following:

  1. A brief description (what is it about?).
  2. A link to news story or article.
  3. Describe the experiment to which the probability refers.
  4. Describe the outcomes of the experiment.

NOTE: You may NOT use the same example as someone else – please check the existing responses before you submit yours.

Extra Credit:  For extra credit, choose an example from your own major or intended career.  At the end of your submission, include the words “Extra Credit:” followed by  a brief description of how the example relates to your major/career choice.

Email notifications – “How do I stop all these emails?”

To change your email setting for this course, do the following:

  1. Go to the Course Profile page by clicking the menu item “Course Profile” at the top of the page (just under the comic).
  2. Select “Membership” on the right side of the screen.
  3. Select “Your Email Options” from  just underneath the name of the course (Spring 2013 – MAT 1272 Statistics – Reitz Profile) in the main part of the page.
  4. Make a selection.  A good setting is “New Topics” (which will eliminate most of the emails, but will still notify you when I post a new assignment or announcement).  The setting you choose is up to you, but I strongly suggest that you do not select “No Email”, as I will be using the OpenLab to make important announcements and so on.