Julia Grove

20:07

I got 0 on one of my trials but that isn't an option

MacKenzie Lenhart

20:40

I also had no face cards or aces but can’t choose 0 as an option

Brooklyn A Duffy

21:17

I just used 1 instead

John R Warren

28:25

https://docs.google.com/presentation/d/1oGDIWjqPKfqo1qZdte0rWNSdM26PVd6Kvxb6vgoLvo4/edit?usp=sharing

Timothy S Opdahl

34:58

83.84%

Samantha Thomas

35:00

Can you work through it also

Alex M Wells

35:09

^

Carly Wolff

35:13

^

Hayat Muse

35:14

^

Kyle Theisen

35:16

^

Sovahn Yong

35:26

^^^

Ryan A Moon

35:27

Havent calculated but z score between 0.03 and 0.04

Elizabeth A Zanmiller

35:29

ok I think we are good on the arrows guys

Sovahn Yong

35:34

^

Kathryn M Meenan

35:51

we didn’t feel like we had enough time or all understood it

Neeraj Rajasekar

35:55

ROFL. We have fun in here

Linda Lubi

36:55

is there a specific chart that we have to look at for z-scores?

Twisha A Boradia

37:05

Can you go back a slide

Eliza G Scholl

37:13

could you slow down a little please?

Elise Cook

37:15

There is a chart on the course site

Lucija L Magurs

37:15

^^^

De Andre T Beadle

37:31

Yes see the course webpage for Z table

Kayla T Truong

37:32

The equation

MacKenzie Lenhart

37:33

The z-score sheet is on the class website so u can find them!!

Ashley Ochoa

38:10

so you basically subtract the zscores?

Idiris Ali

38:36

How did he get (.85)?

Eliza M Lombardy

38:48

Why did I get .14 instead of 1.4?

Timothy S Opdahl

38:50

1-p-hat

Neeraj Rajasekar

39:16

You probably did root() without the /100 [check ur denominator]

Caitlin M Boucha

39:23

1-0.15 = 0.85

Idiris Ali

39:32

thxs

Carly Wolff

39:33

How do u get 0.9192 and 0.0808

Ashley Ochoa

39:44

^^^

Elizabeth A Zanmiller

39:50

those are the scores on the z chart I believe

Elizabeth A Zanmiller

40:26

like the area that corresponds with the 2 z scores he found

Elizabeth A Zanmiller

40:32

(maybe lol)

Neeraj Rajasekar

40:47

Elizabeth is correct

Neeraj Rajasekar

40:58

Those will correspond to areas

Elizabeth A Zanmiller

41:01

aye

Carly Wolff

41:11

Can he go through that

Kyle Theisen

42:18

PLEASE

Elizabeth Kulig

42:24

^

Claire L Laudi

42:49

Sorry so what is the formula? Do you use p hat - p for the numerator

Claire L Laudi

42:54

Or just the bottom

Neeraj Rajasekar

43:36

Claire, you use that twice. P hat = .15, p1 = 1-, p2 = 20

Neeraj Rajasekar

43:50

but the denominator (st error) is same each time

Kayla T Truong

44:02

yes

Hayat Muse

44:03

Yes

ender106@umn.edu

44:28

Z table: https://www.rob-warren.com/uploads/4/5/1/2/45120697/z_table.pdf

Emma C Kopet

45:24

So you convert Z score into the table for both and subtract the small z score value from the larger one to find the area under the curve between the two points

Neeraj Rajasekar

46:10

More or less correct. We'll go thru it

Hayat Muse

47:30

The way I see it is if you ignore the Z-score aspect of this and you were just trying to find out the numbers between 1 and -1 you’d subtract 1 from -1 getting two so if you ignore the fact that you’re subtracting z scores it’s basic algebra.

Idman Adan

47:58

Subtracting the two leaves you with what is in between

Neeraj Rajasekar

48:09

That's true, but don't neglect the importance of the Z score. And I wouldn't bank on that, it won't work every time (negative vs positive numbers)

Kathryn M Meenan

52:34

so for the worksheet it is P(Z greater than 1.4) - P(Z less than -1.4)= .9192 - .0808

Ella Farley

53:09

yes

Claire L Laudi

53:11

Yes

Neeraj Rajasekar

53:13

The math is right, but both are technically Z < 1.4

Neeraj Rajasekar

53:27

the word "Greater than" is a small mistake. It always reports Z < X

Kathryn M Meenan

53:44

thanks!

Ryan A Moon

56:31

in question 6 on the worksheet, it notes the standard deviation. Is this something we do not worry about in the equation this it’s not a factor?

Neeraj Rajasekar

56:44

S = st dev. You need S to calculate SE

Ryan A Moon

56:46

since*

Neeraj Rajasekar

56:48

SE = st error

Elise Cook

59:05

will the SD always be the same just one pos and one neg?

Madelyn L Wolf

59:50

Isn’t the mean the second number in the numerator for z scores?

Kyli R Nault

01:00:17

Don’t we use the t table for mean?

Asiya N Browne

01:00:25

@elise no for example for the cat question he could’ve asked between 10 and 25% in stead of 10 and 20 and then they wouldn’t be the same

Elise Cook

01:00:38

Ok that’s what I thought

Hannah Hagen

01:00:52

I thought t table was only for small samples under 50?

Kyli R Nault

01:01:07

ya its a sample of 40

Elise Cook

01:01:17

he said we would always use t scores from now on, we just haven’t gone over them yet

ender106@umn.edu

01:01:45

I think t scores can be used for small and big samples, z scores should only be used for big samples?

Kyli R Nault

01:01:55

This doesn’t make sense

Eva M Arago

01:02:23

So yeah he should’ve used the t-table ??

Elise Cook

01:02:25

T scores can be used all the time, but you will be less accurate if you use z scores for a smaller means

Julia Grove

01:02:33

t scores are used for small samples because they give you a margin of error

Julia Grove

01:02:45

z scores are accurate only with large samples

Elise Cook

01:02:50

he said in the recorded lecture we will just use t scores after today because you will always be accurate unlike z scores

Neeraj Rajasekar

01:03:17

The math is mostly the same too, btw.

Neeraj Rajasekar

01:03:26

Just the numbers in the tables

Dylan G Brown

01:13:58

Yep

Peach Schmidtlein

01:29:33

So would the final answer to this question be >0.999 ?

Neeraj Rajasekar

01:30:01

Technically, rob has written "greater than or equal to .99," but yes that's fine

Zaynab A Somani

01:30:09

Where does the 0.999 come from? Is that the final answer?

Neeraj Rajasekar

01:30:15

1- .0001 ish

Neeraj Rajasekar

01:30:36

technically, 1 - (.001 * 2) ish

Claire L Laudi

01:31:00

What about .0005 x 2

Zaynab A Somani

01:31:05

Oh ok thank you

Ryan A Moon

01:31:09

That works

Sarah L Davis

01:31:21

I have the same question as claire

Neeraj Rajasekar

01:31:24

"ish" is a very subjective concept. the general point is NEARLY ALL ppl go to the bathroom in that 3. 9 - 5.1 window

Flora Yang

01:31:27

@claire you take the 0.01 to be more conservative because it is larger

Ryan A Moon

01:31:29

claire you’re right

Neeraj Rajasekar

01:31:48

in tests, etc. we won't leave you with imprecise numbers. but yeah .005 * 2 is valid

Ida Ky

01:32:49

#1 on the WS wasn’t on the recorded lecture