Stat 1000: Additional Practice Problems preparing for the Midterm Exam

Published: Thu, 11/07/13

Besides the two sample midterms they have posted, some profs have also posted an additional set of 10 questions to look at before the exam on Saturday.  Make sure you have gone through these 10 questions and the two sample midterms with a finetooth comb.  They are undoubtedly feeding you the majority of the exam questions in an effort to get the grades up.  Here are those sample exams and questions if you haven't seen them:
Did you read my tips on how to study and learn Stat 1000?  If not, here is a link to those important suggestions:
Did you read my Calculator Tips?  If not, here is a link to those important suggestions:
Did you read my Tips for Assignment 1?  If not, here is a link to those important suggestions:
Did you read my Tips for Assignment 2?  If not, here is a link to those important suggestions:
Did you read my Tips for Assignment 3?  If not, here is a link to those important suggestions:
Tips for Assignment 4
You will have to study both Lesson 6: The Binomial Distribution and Lesson 7: The Distribution of the Sample Mean in my Basic Stats 1 book to prepare for this assignment. 
Don't have my book?  You can download a free sample containing Lesson 1 at my website here:
A Warning about StatsPortal
It appears that StatsPortal is not fully functional if you are using Internet Explorer as your browser.  This has ramifications if you are using the HTML Editor box.  I strongly recommend that you use Mozilla Firefox as your internet browser whether you use a Mac or PC to ensure no problems with submitting your assignments.  Here is a link where you can download Firefox direct from Mozilla (it is free):

Do note that every time you exit a question in StatsPortal, the next time you return to it, the data may very well change.  Do not press the "back-up" button on your browser in a question.  That, too, will change the data.  When you are prepared to actually do a question, open the link, keep it open, and do not close it until you have submitted your answers.  There is also some debate whether even pressing "Save Answers" locks the data in place.

You should also have already downloaded the JMP statistical software which was provided with either one of the course options for StatsPortal as mentioned in your course outline.

Make sure you have gone through Assignment 0 completely to learn how to use the interface.  I also suggest you print out a copy of question 8 in Assignment 0 (Long Answer Questions - Part 3) so that you have the steps for saving and uploading files into the HTML editor in front of you.
Question 1

If you are ever asked to decide if a particular situation is binomial or not, remember, to be binomial, four conditions must be satisfied:

  1. There must be a fixed number of trials, n.
  2. Each trial can have only two possible outcomes, success or failure, and the probability of success on each trial must have a constant value, p.
  3. Each trial must be independent.
  4. X, the number of successes, is a discrete random variable where X = 0, 1, 2, ... n.
Hints: If you are reading off numbers from a randomly selected row in the random number table, note that every row has 40 digits.  That is like 40 trials looking for whatever digit you may be looking for.  What is the probability that, at any moment on the table, the next digit is a 0, or a 1, or a 2, etc..

If you are selecting objects, are you sampling with replacement (independent trials) or without replacement (dependent trials)?
Question 2
The Traffic Lights question is standard Binomial stuff as taught in Lesson 6 of my book.  Make sure you are paying attention what colour of light they are talking about so that you use the correct n and p in each question.
Question 3
I tell you the definitions of parameters and statistics at the start of Lesson 4 of my book and I repeat them again in Lesson 7 and illustrate with my question 1.
Question 4
This is Lesson 7 stuff.  You have to always be asking yourself, "Is the problem talking about one individual score X? Or, is it talking about the mean of n scores, x-bar?"  If it is talking about just one score X, is X normally distributed?  If it is talking about the mean of n scores, x-bar, can we assume x-bar is normally distributed?  Why or why not?  If we can assume these are normally distributed, then be careful to use the proper standardizing formula.  Either the X-Bell Curve formula or the x-Bar Bell Curve formula.

Look at my questions 4 through 7 in Lesson 7 for examples.

Make sure you don't round off too much.  Carry at least four decimal places in all intermediate calculations.
Question 5
Your probabilities are exact if you know for sure that the distribution is normal.  However, if you were only able to say the distribution is approximately normal, then your probabilities are only approximate.