Stat 1000: REVISED Tips for Assignment 3

Published: Wed, 10/28/15

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Tips for Assignment 3
Study Lessons 4 and 5 in my study book (if you have it) to learn the concepts involved in Assignment 3.  Don't start working on the assignment too soon.  Study and learn the lesson first, and use the assignment to test your knowledge.  Of course, always seek out assistance from my book, your course notes, etc. if you ever hit a question you don't understand, but try not to be learning things as you do an assignment.  Learn first, then put your learning to the test.

To type in formulas you are using and to show your numbers subbed into the formulas click the button in the toolbar that looks like the Sigma Summation symbol (you have to click the "..." other options button to see the sigma formula input button.  Then click the various buttons to make your fractions and enter the symbols.

Exception: Always do any JMP stuff open-book.  Have my tips in front of you, and let me guide you step-by-step through any JMP stuff.  JMP is just "busy" work.  The sooner you get it done and can move on to productive things like understanding the concepts and interpreting the JMP outputs, the better off you will be.
Question 1
This question is very similar to my question 2 in Lesson 4.

Part (a)
The fraction you get for the height does not give a nice decimal, and so requires rounding.  I suggest you state the answer as a fraction and also give it rounded off to six decimal places.  Then, for the rest of the question, use that 6-decimal place value to do your other computations.  But, round the rest of the answers off to the usual four decimal places.  That way, your answers should be as accurate as they would be if you used the fraction for the height throughout the problem.

In summary, I am saying give all your answers rounded off to four decimal places EXCEPT give the height in part (a) rounded off to six decimal places.

In part (d) you will have to work backwards.  Arbitrarily mark b as some random value on your horizontal axis.  Then mark the given right endpoint further along on the right axis.  Shade the region between b and the given right endpoint.  That rectangular shaded area is what they are describing.  You are given the proportion which tells you the area of the shaded region.  You also know the height of the shaded region (your answer from part (a)).  So, you can establish what the width of the shaded region must be because you know the width times the height equals the area.  Then, you can establish what b must be knowing that Right - Left gives you the width.

For part (e), there is a really easy way to figure out the interquartile range if you think about it.  After all, that is the width of the middle 50%.
Question 2
I strongly recommend you read my section in Lesson 4 about the Z Bell Curve Ladder and the X Bell Curve Ladder and make the ladder every single time you have a bell curve problem.  Then climb up or down the rungs.  Many students are guilty of not thinking a problem through, and consequently looking at Table A too soon.  The ladder trains you to focus on the fact that Table A deals with z scores and Left Areas, but your problem may be interested in something else.

You will be using Table A for much of this assignment.  Here is a link where you can download the table if you have not already done so:

This is very similar to my Lesson 4, question 5.  Make sure you have done all of those questions first and have confirmed by repeated attempts, that you can get them 100% correct every time before you attempt this question on the assignment.

IT IS IMPERATIVE THAT A STUDENT CAN CONSISTENTLY GET MY QUESTIONS 5 AND 6 CORRECT EVERY TIME WITHOUT EXCEPTION.  BE HARD ON YOURSELF.  Students who make mistakes on this stuff, and find themselves saying things like, "Oh, I forgot to subtract from 1; or, oh, I didn't realize that was the right area," are just setting themselves up to get most of the exam questions wrong.  Always use my bell curve ladders to help you focus on the problem and always draw a diagram to visualize the problem.
Question 3
This is very similar to my Lesson 4, question 6.  Make sure you have done all of those questions first and have confirmed by repeated attempts, that you can get them 100% correct every time before you attempt this question on the assignment.

IT IS IMPERATIVE THAT A STUDENT CAN CONSISTENTLY GET MY QUESTIONS 5 AND 6 CORRECT EVERY TIME WITHOUT EXCEPTION.  BE HARD ON YOURSELF.  Students who make mistakes on this stuff, and find themselves saying things like, "Oh, I forgot to subtract from 1; or, oh, I didn't realize that was the right area," are just setting themselves up to get most of the exam questions wrong.  Always use my bell curve ladders to help you focus on the problem and always draw a diagram to visualize the problem.

For part (a), note that I also do a percentile example in my question 7.  As I say in my question 7, the 80th percentile, for example, is the z-score that has 80% of the area to the left of that score.

In part (d), do note that it is b they want, not -b, so be sure to determine the value of the z-score on the right side of the region.
Question 4
Make sure you have studied all my X-Bell Curve problems (questions 9 to the end) in Lesson 4 before you attempt this question.  Make sure you use the X-Bell Curve Ladder to help you work your way through each part of this question.

You also need to know the 68-95-99.7 Rule taught earlier in my lesson (questions 3 and 4 in Lesson 4).  But, only use this rule to solve part (e).  Never use the 68-95-99.7 rule unless you are clearly told to do so!

Part (h) is all about z scores.  The higher your z score in a normal distribution, the better you did relative to others.  See my question 14 in Lesson 4 for an example of this principle.
Question 5
This is a question best solved by Venn Diagrams.  Make sure you have studied that section in Lesson 5 of my book and have done questions 14 to 18 before you attempt this question.  Make sure you have definitely looked over my examples of how to prove two events are independent or not in those questions (as well as others earlier in the lesson). 

This question is quite similar to my question 18.
Question 6
This question is a good example of a 2-way table problem.  It is sort of a combination of my Lesson 5, questions 4, 5 and 6.

Parts (a) and (b):
I show you how to determine a Sample Space through the use of two-way tables if necessary in Lesson 5 of my book.  Note that all you are asked for is the sample space in each part, don't forget to use those squiggly brackets "{}".

For example, here is the sample space for the outcome of flipping a coin twice where H=heads and T=tails:  {HH, HT, TH, HH}.

Don't state the probabilities!  You are not asked for the probabilities. 

Focus on what you are asked to select.  Is it just the colour of the candy you are interested in (Purple, Yellow or Red?, P, Y or R). Is it the flavour of the candies?

Parts (c) and (d):
Now, you are asked to compute probabilities.  You can use the actual counts of each candy and the sample spaces you found in the previous two questions to help here.

Part (e):
You are asked for first is lemon OR second is cherry.  NOT AND!

I think it is a good idea to use my "check-mark method" that I show you in my Venn diagrams section when dealing with AND or OR.  In your sample space, check off all the outcomes that belong to A.  Now go back and check off all the outcomes that belong to B.  This might mean you are checking off the same outcome twice.
  • If you want A and B, add up all the probabilities that have been checked off twice.  (Those are the outcomes that belong to both A and B, as required.)
  • If you want A or B, add up any probability that has at least one check mark.  (Those are the outcomes that belong to at least one of A or B, as required.)
Part (f):
Very similar to my Lesson 5, question 4(f), for example.  I would insert a table from the extra part of the toolbar to summarize this probability distribution.