Greetings all!
Here's where you can post your questions to Barry.
I'm teaching Math 60, 65, and 95 at PCC as well as Math 111 and 243 at Mt Hood.
Be sure to read the "First Post" in the archive, if you haven't used this blog before.
I hope you all have a great term.
Barry
Subscribe to:
Post Comments (Atom)
Posts
Elizabeth Lambert
ReplyDeletemath 243 section 3
MHCC
Are we supposed to do the first activity assigned on our own, or did you already assign us groups?
You are doing the "Puzzle activity" with a temporary team of the people you sat with yesterday. If you didn't turn it in during class, it is due at the beginning of class Thursday, after you and your temporary team decides which copy to turn it for grading.
ReplyDeleteKelly Bettendorf
ReplyDeleteMHCC Math 111
I am stuck on 2.1 #15
I do not understand how to find F(1)/F(3)
let F(x)=3+2x^2 find f(1/3) & F(1)/F(3)
Use the numbers in the parentheses (the input) and the formula to find F(1/3), F(1), and F(3) separately. Then divide the last two to find F(1)/F(3).
ReplyDeleteWhoops... accidentally posted in the Summer Term section.
ReplyDeleteHey Barry,
I'm in your Math111 class at MHCC. Im having trouble registering with WileyPlus: MHCC doesn't come up as an option when I put it into the "Find Your Class" field...
How or where do I find your office for help before class. I'm completely lost at this point. Everything you cover on the board I get; however, once I look at the homework it's completely different and I honestly don't know how to do 90% of it or even where to start. At this point I need serious help as I'm falling far behind and if this is the case I need to drop this class and change my degree.
ReplyDeleteOffice Time at 1 pm in the Math Dept. Lobby
ReplyDeleteWhere is the math lobby?
ReplyDeleteKristin Bartley
ReplyDeleteMth 243-03
I am stuck on PS probability #5 c and d
Nadia Anuchin
ReplyDeleteMath 111, Section 10
MHCC
Please help me with Section 1.3, problem #23.
Thanks
Barry
ReplyDeleteI am almost done with the take home quiz but I am stuck on the third problem. I know you said to use the Kool Aid stand example but im confused. Is there another example I can look at?
Sandra Lanzieri
Math 65 mw 9am
SE Pcc
Sandra,
ReplyDeleteThere are no examples in the text that involve revenue and costs, but Sections 5.2 & 5.4 have several examples of solving linear systems. Perhaps that will help.
Barry,
ReplyDeleteI am almost done with the take home quiz, but I'm struggling on number #2 (On the kool aid stand we did in class you said that mathematically the domain and range is "all real numbers" and in the real world, the domain is n>0 and range is c>1. So for number 2, do you want us to do the domain and range mathematically??? or like in the real world??? I hope I didn't confuse you.
Thanks
Nadia Anuchin
Math 111/Section 10
MHCC
Do "real world" and say that's what your answer is.
ReplyDeleteThanks!!!
ReplyDeleteAlso on that same quiz, for number five, to write a formula for a piecewise defined function, is there an example in the book that I can use?
Thanks again, I would love to come to office hours, but it's hard to find a babysitter, I've got 4 kids and the youngest is 3 months.
Nadia Anuchin
Math 111 / Section 10
MHCC
Go to the section in the text on piece-wise defined functions for some examples.
ReplyDeleteThank you!
ReplyDeleteHey Barry, I'm having a really hard time on the take home quiz #5, the piecewise function. I looked in the text, and it covers a little bit, but I still don't understand how to make the formula. Any other examples online you might know of to use that helps?
ReplyDeleteThanks,
Danielle Cramer
No more examples, just a clue or two:
ReplyDelete1) You're making it too hard.
2) "Piecewise" means it has one formula for each piece of the domain. I've given you two formulas (one extremely easy) and two corresponding pieces of domain.
... Just write it out!
Hi Professor, I am in your MTH243-03, I do not know how to find the z-score for the area of 35% in the last example on page 42. Can you explain it to me?
ReplyDeleteI believe that 35% equal to 0.3500 of the area to the left right? How do you come up with the z_ score of -0.39?
Thanks
Look for the 35% (as .3500) in the middle of the table. If it isn't there exactly, pick the number closest to it.
ReplyDeleteNow look at the row and column headings for that. Umber and add them. That will be your z-score.
I checked it up and see that -0.40=0.3446, -0.39 =0.3783, -0.38=0.3520 . I do not know which number to choose for the area of 0.3500. Why do not we choose the number -0.40 instead of -0.39=0.3783 or 0.38=0.3520 ( -0.39=0.3783 is too much larger than -0.38=0.3520 or -0.40=0.3446 which are the closest to 0.3500?. Hope you are not confused with my question.
ReplyDeleteThanks
I mean why don't we choose -0.40 or -0.38 instead of -0.39 as its value is too much larger than -0.40 and -0.38
ReplyDeleteThanks
It sounds like you are confusing the numbers in the middle of the table (areas or probabilities) with the numbers on the edge of the table (z-scores).
ReplyDeleteI know how to get the z-core from the known area, I just do not know what exact number I should pick up as you said pick the one closest to the known area, but in this case i see that the area value of 0.3500 is closer to -0.40(0.3446) or -0.38(0.3520) than -0.39(0.3783). I mean which number we should choose, bigger or smaller than the known area. That is my concern, not how to get the number.
ReplyDeleteThanks
Choose .3520 since its only 20 ten thousandths from .3500. So the z-score is z = -.38. The value .3446 is 54 ten thousandths away.
ReplyDeleteIt's about choosing the closest value to .3500, then using the corresponding z-score.
That is the exact answer I needed. So we should choose 0.3520 which has z-core of -0.38 right? But I see in the last example on page 40 the z-score for 0.3500 is -0.39 (0.3783). That why I am confused.
ReplyDeleteThank for your promt ressponse.
I am sorry. The last example is on page 42 not 40. My bad.
ReplyDeleteUse -.38.
ReplyDeleteThanks. I got it.
ReplyDeleteBarry!
ReplyDeleteWhat the heck is the answer to #7????
Pls help!
This is BreaAnn
You have to think, "How does this relate to the FOUR coin flip experiment" and what kind of random variable this is.
ReplyDeleteDon't be afraid to use the appropriate cdf calculator command.
Then it's easy.
Hi Professor
ReplyDeleteAbout math 243
How can we differentiate between binomal random variable problem and continuous random variable problem? It both seem alike to me.
Thanks
First , binomials are discrete, meaning they are about "counting" where normals are continuous, they are about "measuring".
ReplyDeleteAlso, to understand a binomial, you need the number of trials (n) and the probability of success (p). For a normal, you need the mean and the standard deviation.
Hope that helps.
Snowing days in a year would be considered discrete or continuous variable? I thinks it is continuous variable,but at the same time I think it could be a discrete variable because the number of days are discrete variable right?
ReplyDeleteLook at the information given ...
ReplyDeleteThanks.
ReplyDeleteBarry
ReplyDeleteOn our homework section 7.4 we are to do 1-109
but problem # 97 is dividing I am confused. I looked at my notes and I dont see where we divided. The example in the solution book is very confusing! Help
Sandi Lanzieri
math 65 mw 9 am
PCC
Sorry, bad problem slipped through the cracks.
ReplyDeleteSkip it.
thank you yeah lol
ReplyDeleteSandi Lanzieri
Hi Barry:)
ReplyDeleteFor MTH243
ReplyDeleteFor the problem set (EDA) should I do like activity that we have in class? Can you tel me what way i should do it?
Yes, like the activity. But do ALL the things I showed you in class, including a stem plot and the Empirical Rule.
ReplyDeletefor MTH 243. I don't understand much about empirical rule. Can you tell me more
ReplyDeleteHi Barry...
ReplyDeleteMth 243
Can you please help me understand the outliers a little better. I am completely lost with those. I am on PS: EDA #1.
Thank you.
Did you do the calculations using the standard deviation and the IQR?
ReplyDeleteUsing the Standard deviation: (x-bar - 2*s to x-bar + 2*s)
Using the IQR (Q1 - 1.5*IQR to Q3 + 1.5*IQR)
If not, look at the part on EDA in the supplement and see me before class.
Melanie S.
ReplyDeleteMth111
hood(T/R 3-5)
Barry, Giving this another try. Maybe I posted in the wrong place. I am hoping to get an example of #4 B&C
Here is as far as I have got.
b)ln10/3= ln10-ln3=1.204 but now what? how do I check this?
c)7ln(0.5)=-4.852 Again not sure what to do from this point
Hi Barry;
ReplyDeleteI'm having a lot of trouble with Quiz 3, #4C. Is there an example I can use? Please help. Thanks.
Nadia Anuchin
MHCC
111-10
Some folks in MTH 111 are having difficulty with problem 4 of Quiz 3.
ReplyDeleteI recommend you look at: a) the similar problems in your notes (we used base 10, but they work the same), b) Examples 3 and 4 on page 181 (top page numbers) of the text, and c) the laws of logarithms in your notes and on pages 182 and 183.
Barry;
ReplyDeleteSo for 4c, can I do something crazy like ( ln3 - ln2 / ln2) to get 0.5???
Nadia Anuchin
MHCC
111-10
Consider that 1/2 is the same as 2 ^ (-1).
ReplyDeleteUse that instead of 1/2 in the problem.
OK, thank you so much.
ReplyDeleteNadia Anuchin
MHCC
111-10
I sent you a proposed extra credit on your pcc account because I'm to blonde to figure out the mhcc one. :( Class 111
ReplyDelete-Jamie C
Test you get this?
ReplyDeleteI apologize, I'm not in your class, but Veronica in MTH111 suggested I try (I'm in MTH251)...never posted to a blog, not sure how it works. Will trade a riddle for confirmation of my already obtained answers.Please respond to perhapsmaybenot@hotmail.com if possible. Thanks, Jocosa
ReplyDeleteEmperical Rule Help.
ReplyDeleteMath243
xbar= 7.3
minx= 3.3
So from there I add and subtract to get (a,b) answer. Then find how many numbers are between A and B then divide that by n multiply by 100 to get the percent rate of 1 std dev. Do I then take 7.3-3.3=4(2) to find 2 std dev? 7.3-3.3=4 (3) to find 3 std dev??????
Assuming x-bar is 7.3 and std dev is 3.3:
ReplyDelete7.3-1*3.3 to 7.3+1*3.3 is the range for one std dev
7.3-2*3.3 to 7.3+2*3.3 is the range for two std devs
7.3-3*3.3 to 7.3+3*3.3 is the range for three std devs
In each range, count the number of data values from the sample inside the range, divide by the sample size n, then times by 100%. The closer your percents are to 68%, 95%, and 99.7% the better.
Nevermind, I got it!
ReplyDeleteMth 243
ReplyDeleteProblem Set: Sampling Distributions
#3
Suppose the national average cost of a textbook for students at community college is $86.38 with standard deviation of $12.55. What is the chance that the forty textbooks six random students have to buy next term have an average cost of less than $75.
I am not getting the same answer as the answer sheet.
Math 243
ReplyDeleteAbout Correlation and Regression
How do we state the linear function which has a negative strong correlation and r2=56%,when we get a predicting X value and Y value , the outcome is not close to the Y value in the table?( less than 20% compared to the Y value of the table). Can we say that it is a reasonable line for the data?
Thanks
And we know how strong or weak a correlation is based on r value, but at what value of r2(%) is considered a "good fit" for a correlation?
ReplyDeleteOn problem 3 of Sampling Distributions:
ReplyDeleteDid you divide the standard deviation by the square root of 40, to get the standard deviation of x-bar?
The closer r is to +1 or -1, the better the fit.
ReplyDeleteThis most often happens when |r| > 0.7.
That means r^2 > 0.49 (about 50% or more), because r^2 is "the square of the correlation, r".
I would double check your calculations and consider the above.
Barry
ReplyDeleteCan you tell me what Calculator I should buy for math 95?
I also want to take the time to say Thank you for making Math 65 such a great class! You are a wonderful Instrutor.
Sandi
math 65 pcc SE
on EDA problem. the data consider is "bell curve" have to have mount shape, symmetric, and outlier no more than 5% right? but on EDA problem #2. The data has skew left. but why the answer that the data is normal ( bell curve). Can you help me out.
ReplyDeleteAre you being too picky about the skewnwss of the data?
ReplyDeleteRemember, it's a sample ... look at all the evidence. Then decide, and don't expect things to be perfect ... it won't be!