Rubric (grading guide) – OpenLab Final Project

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The link below will take you to the grading rubric for your OpenLab Final Project.  The project is worth 15 points altogether, the equivalent of three OpenLab assignments, and the rubric explains how I will assign those 15 points (5 points in each of 3 different categories). You may wish to invest 15 minutes of your time in reading through it — knowing how I will grade the project can be a great benefit when you are setting out to complete it (knowledge is power!).

Grading Rubric for OpenLab Final Project: Final Exam Study Guide

Study Guide For Problem # 6

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Ramsuresh Rampersad

I’m working on problem # 6

6.) A box contains 30 marbles: 15 red, 10 blue, and 5 green.

a) two marbles are selected with replacement. Find the probability that both marbles are red.

b) Two marbles are selected without replacement. Find the probability of first selecting a blue then a green marble.

SOLVING PART (a)

To solve part (a) of this problem first considered the following:

1. There is a total of 30 marbles in the box.

2. There are 15 red marbles.

3. The marbles that are chosen are being replaced.

If you keep these three ideas together, it will help you to avoid confusing the different color  marbles and second, that you don’t keep the marbles, they are being replaced in the box. Alright! Having said that, let’s begin solving this really simple problem. Don’t worry, we’ll go step by step. And as you follow these simple steps, which I am absolutely sure you can, you will soon discover that this problem is a walk in the park and you can solve this and others just like it.

Step 1: As we discovered earlier when we took those three things into consideration. There are 15 red marbles in the box. Now, we also know that we are going to select two marbles. But first we have to find the probability of selecting the first red marble. Doing this is really easy. Here’s how it’s done. We both know that there are 15 red marbles in the box, and that there is a total of 30 marbles in that box. So we dip in take a marble out (no peeking please! lol). What are the chances that you have just pulled out a red marble? Well that’s easy. Since there are 15 red marbles and a total of 30 red marbles. The chances or probability that you just pulled out a red marble must be (you said it!) 15 out of 30. So the probability that your first marble is red is 15/30. Let’s make that into a smaller fraction 15/30 = 1/2.

Step 2: We’re doing good, told you it was simple! Hey you can’t take that marble with you. So now please replace that red marble in the box. So now since you’ve replaced that red marble we now have once again, that’s right 15 red marbles. I know you’re thinking it and you are absolutely right, our total number of marbles is still 30. So don’t forget, we have a total of 30 marbles in the bag, including 15 red marbles because you replaced the red that was initially taken out. Awesome!

Step 3:  Ok, we’re doing great. We are on the road to finding the probability of choosing a second red marble. And guess what we’re both right because, it is exactly the same as the first situation. We’ve replaced that red marble we took out. Therefore, the probability of choosing a second red marble is also 15/30 = 1/2. Doesn’t seem like a problem at all does it?

Step 4: I know you’re gonna be like what! When I say this, but yes you’ve successfully come to the last step of this half of the problem. This is so easy you’re gonna laugh and say damn why didn’t I choose this problem to do…lol. Guess what? Now all you have to do for your final answer is to multiply those two probabilities you just found above.That is: 1/2 * 1/2 = 1/4. And you have just successfully solved the first half of this problem.

Answer = 1/4

SOLVING PART (b)

To solve this part of the problem first consider the following:

1. There is a total of 30 marbles.

2. There are 10 blue marbles, and

3. There are 5 green marbles.

4 When a marble is removed it is not replaced.

Step 1:  This part is just as easy. Start by following the same principles that we did earlier. That is separate the information as  above. Kool, so let’s get started. We’re going to take two marbles out the box, and this time we’re looking for the chance or probability of taking out a blue marble first. Hey this time you can keep the marble, we’re not putting it back.

So let’s see, how many blue marbles do we have, yes,10 blue marbles, and as you know we have a total of 30 marbles in the box. OK, so go ahead dip in. So did you get a blue one? What’s  the probability of selecting the first blue marble? Well, since there are 10 blue marbles and there is a total of 30 marbles. That’s right, it is: 10/30. It’s that easy. And 10/30 can be simplified 10/30 = 1/3.

DO NOT FORGET WE’RE NOT REPLACING THE MARBLE IN THE BOX. WE’RE PLAYING FOR KEEPS THIS TIME! So how much marbles does that leave us in the box? We had 30, you took one, therefore, we have only 29 marbles left in the box and NOT 30. Alright I can live with that!

Step 2: You get another chance, remember we’re choosing 2 marbles out of the box. We took one out that you kept leaving us with 29. And now we’re going to take another one out. Now what are the chances or probability that it is a green one? We’ll that easy too. I think you know where I’m headed. Yes, since there are 5 green marbles, the probability of selecting the first green marble is: 5/29. It’s out of 29 because we didn’t replace the first one we took out you were allowed to keep it. If we reduce 5/29 you will get a mixed number so it’s best to leave it as it is.

Step 3 : Well, what do you know? We have successfully reached the last step of this half of problem #6. And again all we do in this step is we multiply both probabilities to find our answer of first selecting a blue and then a green marble: 1/3 * 5/29 = 5/87. And that’s it. You have just completed # 6. And thank you!

Answer = 5/87

 

 

 

 

WeBWorK #12 UPDATE

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Hi everyone,

A few people were having trouble with problem #1 — webwork was not accepting the test statistic, even though their calculations were correct.  I have updated the problem to give a more accurate xbar (that is, it now shows 3 decimals instead of 2), and if you use this to calculate the test statistic it should solve the problem.  If it doesn’t, please let me know.  Apologies for the inconvenience.

Regards,

Mr. Reitz

OpenLab final project: Final Exam Study Guide

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EDIT:  Since all the Final Exam Review problems are now spoken for, please choose a problem from Exam Review #3, problems 6-12.

List updated Thursday, May 16, 2pm to include current list of CLAIMED PROBLEMS (see the bottom of the post for the list).

Assignment (Due Thursday, May 16, 2:30pm).  Create a study guide for one problem on the final exam.  This project will take the place of all remaining OpenLab assignments (it will count for 3 assignments overall), and consists of the three tasks described below.

Your audience is your classmates and other CityTech students taking MAT 1272. 

Tasks

  1. Choose a problem, and claim it by replying to this message.  Choose a problem from the final exam review sheet that you would like to work on – but do NOT choose problems #17, 21, or 26 (these will be covered in the final days of the semester).  Only one person may work on each problem, and they are assigned on a first-come, first-served basis.  To claim your problem, reply to this post and include your name and the problem number you want.  Please look through the replies that have already been posted – if your problem is already taken, you must choose another.
  2. Solve the problem.  Write an explanation, in words, of each step of the problem, and then show the the results of each calculation. Include any advice you can think of that might help fellow students, for example how you knew what type of problem it was, or how you knew what to do next!
    Stuck?  Ask for help!  You are encouraged to talk to your classmates, to tutors, or to Mr. Reitz about your problem and solution.
  3. Create a new blog post with your solution. Do NOT reply to this post with your solution.  Instead, create a new blog post with your solution.  Your grade for this assignment will be based on your post.  Instructions for creating a blog post appear below.

INSTRUCTIONS FOR CREATING A BLOG POST
Read the following instructions carefully and completely. 

You will create a new blog post on our OpenLab site.  You create a new blog post by logging in to the site, and clicking on the gray circle with a “+” plus sign at the very top of the screen (and selecting “Post”).  Once you have created and published a post, you can find it on the Home page of the site. You CAN make changes to a post, even after it appears on the site.

Your post should include the following:

TITLE: Study Guide for Problem # (insert your problem number here)

BODY: include the following in the body of your post

  • your name
  • the problem you chose to work on (please include the entire problem)
  • step-by-step solution, with explanations and results of each calculation

TAGS: please add the following tags to your post (using the box on the right).  1. “study guide”, 2. topic (for example “hypothesis testing”, or “probability” – there are many options, and you can include more than one), 3. plus any other tags you think are appropriate

Don’t forget to click the blue “Publish” button on the right side of the screen to make your post public.  You can also use the “Save Draft” option, which will save it without making it public (to find it later, go to the Dashboard and click “Posts” on the left side).

Feel free to post questions on the OpenLab if you have them.

 

 

CLAIMED PROBLEMS (Updated Thursday, May 16, 2:00pm):

1 Glen Moore
2 Julieann McGonigle
3 Tanzima Mursalin
4 Erica Press
5 Barbara George
6 Ram Rampersad
7 Brianna Mahoney
8 Jenny Soriano
9 Valerie Cabezas
10 America Hernandez
11 Craig Shaw
12 Anil Dipu
13 Adriana Mandelburger
14 Candice Wright
15 Anthony Marc
16 Melissa Alteon
17 xx
18 Garfield Gray
19 sessa
20 Dania Elder
21 xx
22 Zinaida Ashurova
23 Fatima Elmachatt
24 Mary Fung
25 Mohammed Ahmed
26 xx

Exam Review #3 (Problems 6-12 only)
6 Elizabeth Fitts
7 Laticia Bourne
8 Jacky Xu
9
10
11
12 Edward Zheng

URGENT: EXAM #3 POSTPONED UNTIL NEXT TUESDAY

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The short version:  Exam #3, which was scheduled for tomorrow (Thursday, 4/25), is now postponed until next Tuesday, 4/30.

The long version:  My daughter Sierra is undergoing surgery on Tuesday and so I will not be in class (luckily it is not a major operation, just a followup to a prior procedure, but she will be under full anesthesia and will stay in the hospital all day).  It makes more sense to have the sub give the exam, rather than cover new material.  Therefore, tomorrow in class I will be covering new material (which will not be on the exam).  I do have office hours tomorrow from 11:30 – 12:30 (in N707), and I will do my best to come to class a few minutes early and answer questions.  For those of you who requested additional time to study, you are in luck!

My apologies for the very late notice – we weren’t informed of the surgery date until today.

-Mr. Reitz

WeBWorK #11

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Hi everyone,

WeBWorK assignment #11, which is based on the material covered in class today (“sample means”), is now available.  It will be due next Tuesday evening, 4/30/13.  Please do not work on it until after the exam on Thursday.  Indeed, it would be best if you did not even read this message until after the exam.  Best of luck with your studying.

– Mr. Reitz

Update on WeBWorK #10

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I have rewritten the WeBWorK #10 assignment – the problems are based on section 5.5 (which we studied on Thursday), and are much more similar to what will be on the exam next week.  The assignment is now available, and is due on Tuesday night at midnight.  Don’t hesitate to write if you have questions.

Take care,
Mr. Reitz

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

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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

WeBWorK #9 UPDATE

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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)