Today's Slides: June 11

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Today's Slides: June 8

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BOB

Our unit Statistic is confusin... because of many formulas and the different calculator command.... And some of the problem I dn't know how to do it, but yesterday's review and today's class really helped me.... now I kinda understand which formula im going to use or calculator commands in each problem..... I hope I dn't get confuse on tomorrow's test and atleast I could get 50% on the test....... ----->>> wishing u all best of luck!.... :S

BOB

Well, it is the day before our test and i am starting to get nervous, I think that the unit was difficult, but once i started understanding the formulas it started to get easier, but im still having problems. I think that it was to get the idea of an example and using it for another question, but it usually doesn't work, you have to really understand what is happening. Well, GOOD LUCK everyone!!

Bob

i think this unit has been the hardest one we're done so far this year. There are alot of formula's that you need to remember and if you mix them up you could get very confused. When we first started statistics i thought it was pretty easy, things were just making sence. As the unit went on Mr K kept introducing new things and i had no idea what was going on. But when it came test time i felt i was ready and then the test was postponed until after spring break thats what screwed me up. When we came back i had no idea how to do anything and was really not looking forward to the postponed test. Now going into the night before the test i really believe that our last two classes have helped me learned more about the things i didn't know. Goodluck to all on the test tomorrow because i know i'll need it.

Today's Slides: April 12

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BOB

Well yet agin another BOB, I feel as if I just did one..haha. But anyway this unit was different it took a while to wrap my head around it, for the math itself isn't difficult, it's understanding the amaterial and remembering what to do. I really wish we could have done the test before spring break because I felt that I knew most of the stuff, but now i feel a little lost, when I went back to try to do old questions it was ahrd to remember. I couldn't remember some stuff I almost felt as if I had to re-learn it. Hopefully I do well on this test, I really wnat my term mark to go up. Best of luck guys!
-Britt<3

BOB

OK... so statistics... Well before i start i would like to say sorry if i haven't been up here or anywhere else like the DEV blog thing.. my computer is sick so i had to kidnap my grandma today and force her to bring me home with her so i can use hers... so i can BOB.. YA bob..
So i guess the first thing i would like to say about STATISTICS is that it has frustrated me more than once this term and that I am glad it is almost over.. One thing i noticed was that it was really difficult going through it once with the class and Mr.k. For a while i thought i could possibly fail this unit. The thing that i noticed though was that when i went though it a second time ( on my spare time of course) from the beginning of chapter to the end, it was so much easier because i already had the knowledge that Mr.k had already gave us in my mind. The text book gave me that extra little push into the "I-know-what-I-am-doing-now" zone. I still believe i might have some problems, this isn't an extra easy unit. But the text book helped.. its great to know its not just a paper weight AND it taught me some neat things. Like how i knew that you should clear the Lists and turn off the Y plots when you shade norm. So that's my little blurb about statistics.. GOOD LUCK ON YOUR TEST!!!

Today's Slides: April 11

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BOB

Just like others said, Statistics was really a hard unit. There where a lot of times that I don't even know what to do or I could not follow the steps that we have to do on the calculator, but in the end it was okay. For me to pass this upcoming test, I really need to study. I think the key to pass this test is to know what formula to use on a certain question and to understand the question itself. Like everybody else said, this is really a confusing unit, so good luck to you guys. I hope we all do well.

BOB

In the unit of Statistics, everything is pretty complicated. Analyzing the problems carefully is one thing that we should always do. This unit also involves probability, which makes it more complex in understanding. The topic that I am comfortable and confident with are z-scores and the confidence intervals. Learning Statistics also involves different calculator functions which will be remembered if we understand the meaning of the problems that we have. Statistics is also important because it is used by different professionals in the real world like teacher applying that knowledge in the marks of their students. Speaking of marks, I hope I get a good mark in our upcoming test tomorrow??.. Oh well, good luck to us! ;-)

BOB

Wow this unit is so hard, its like every question u do is like different.After the pre-test it hit me hard.Like i can only answer 30 percent of the question.Aleast the unit isn't hard as proability.But yeah im like freaking out on the test.I did my homework and reviewed some question ,but until the pretest its just different.

B O B

I think that our unit Statistics is a hard and confusing unit, because of the different calculator commands that we have to learn how to use. But some part of it was easy to understand and use on problems, like finding the 95% confidence interval and the margin of error. What I think about our pre-test this morning is that it was short but confusing, I didn't even get the answer for the last page questions. If our test is tommorow, I really have to study tonight... and I'm gonna start now. ~(_8(])

BOB

I guess i'll do a BOB as well, just incase we do have the test tomorrow, which I hope doesn't happen. So, today in class we did the pretest and I think we were all confused about it x| So yeah, I think that's why we shouldn't have our test tomorrow. Anyway, overall I thought that statistics was okay, I think that the unit overall was okay. It took awhile to get, but eventually I got it. And that's basically it, yup. Kay, bye!

BOB

Hello! So I think... I THINK we have to BOB. I'm not too sure, but I'll write a BOB tonight just in case our stats test is tomorrow! Well statistics was a very long and hard unit! I feel confident in some areas of statistics, but not all. I feel like I'm most confident with z-scores, and the 95% confidence level. The other topics just confuse me sometimes. I really have a hard time approaching the question, and figuring out which function to use on my calculator! normalpdf, normalcdf, binompdf, binomcdf, invnorm!!??! But I'm trying to do many different problems so that I could understand it more. And it's working! And I HOPE I get a good mark on the test! .. if our test is tomorrow!

scribe

So we did our statistics pretest today! Mr. K wasn't there and we all got different answers and were not sure about the problems. So I'm not going to do the problems since we don't know if there right or wrong! So I'll continue my scribe tomorrow!

So it's tomorrow now! and Mr. K was there and we went over the pretest. aaand here it is.


















and the next scribe is cris_J

Monday's Homework

Here it is ...





And the answer are ...

Confidence Interval

On Thursday, we talked about confidence intervals.

A confidence interval gives an estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data.

We had this problem…

Some Senior 4 students in a large high school want to change a tradition at graduation. Instead of wearing the usual cap and gown, they want to wear formal clothes. A quick survey of 96 randomly selected students shows that 41 prefer formal wear.

To answer this question, construct a “confidence interval”, most often a “95% confidence interval”.

Find the probability (P), the mean (µ), and the standard deviation (σ) first.
p = 41 / 96
= 0.43


µ = n ∙ p
= 96 (0.43)
= 41.28



σ = √ n ∙ p ∙ (1 - p)
= √ 96 (0.43) (1 – 0.43)
= √ 23.5296
= 4.851

For data that have a normal distribution with mean and standard deviation, a 95% confidence interval is:

µ ± 1.96σ

This is the range of values that lie within 1.96 standard deviations of the mean. The probability that a particular data value lies in that range is 0.95. This is shown in the graph.

95% confidence interval = µ ± 1.96σ
= 41.28 ± 1.96 (4.851)
= 41.28 ± 9.508

---

= 41.28 – 9.508
= 31.772

or

= 41.28 + 9.508
= 50.788

We write it this way: (31.772, 50.788)

= (31.772 / 96) × 100
= 33%



= (50.788 / 96) × 100
= 53%

And we write it this way: (33%, 53%)

With 95% confidence, we know that between 33% and 53% of 96 students prefer formal wear.
Now, find the Margin of Error and Percent Margin of Error.

The margin of error is the proportion that we add to, and subtract from, the mean to construct the confidence interval.

For a 95% confidence interval: Margin of Error = ± 1.96σ

1.96 × 4.851 or 9.508 represents the half-width of the interval. This is the margin of error. To express this as a percent, we divide it by the sample size, which is 96, and multiply by 100.

% Margin of Error = ± (9.508 / 96) × 100
= ± 9.904%

Is it possible that a majority of students prefer formal wear?
** Yes, but not likely, because the high end of the 95% confidence interval is just 3% over the half of the sample size and the Margin of Error is a little bit high. When you conduct a survey, the smaller the Margin of Error, the better the results of the survey.

The next scribe is Donna (",)

Today's Slides: April 5

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To see a larger image of the slides go here. When you get there you'll see a button in the bottom right-hand corner that says [full]. Click it and the slides will display in full screen mode.

Statistics

Today we refreshed our memorys by doing some problems on probability.

The probability that a student owns a cd player is 3/5. If eight students are selected at random, what is the probability?

a) exactly 4 of them own a cd player

To do this we have to use "Binompdf." So if we want to do this on the calculator you press:

• 2nd, DISTR
• find Binompdf or if you have a TI-83 press 0
• Then we use the formula - Binompdf(# of Trials, Probability of success, # of success)

So it should look like this:

Binompdf(8, 3/5, 4)

You hit enter and your get .2322 or 23.22% and thats your probability.

We also learned how to Calculate probabilitys using normal approxamate of binomial distribution.

Example

A basketball player is successful on her freethrows 75% of the tim. Determine the probability that she makes at least 7/10 free throws.

So using normal approxamate of binomial distribution we have to know that:

• N = Number of trials = 10
• P = Probability of success = .75
• # of Success = 7

So we have to know thes three formulas to do this:

M = N*P

Failure = N(1-P)

S.T = Standard Deviation = S.D = Square root (M(1-P)

Z score = Z = (# of success - M)/S.D

Now we put all the info in and find the Z Score

we get the S.D of -0.3693. So now we use shadenorm to find the probabilty. So we go Shadenorm(-0.3651 , 5) and get the probability of 64.25%

Next scribe is Cris J.