Real Quick Math Help - FreeiPodGuide Forums

OldManWrigley

28-01-2007 20:57:06

I know I know, it's not a homework board and I've made to many threads, ya, ya. I have school in the morning, and I just can't figure this shit out.

Distribution of scores on an exam is closely described by a normal curve with mean of 100. The 16th percentile of this distribution is 80. What is the Standard Deviation?

WTF. That's so little information. Anyway, anybody know? (

J4320

28-01-2007 20:58:04

Have you tried www.chacha.com ?

lol

Some of them are math majors and they'll do it for you if you ask.

JUNIOR6886

28-01-2007 21:05:29

Status Connecting ...
Status Looking for a guide ...
Status Connected to guide KerryannB
KerryannB Welcome to ChaCha!
You hi i need to find a way to solve an algebra problem
KerryannB Ok..I'll get you some algebra help sites.
You f(x) = 3 + X + e^x
You i need to solve for x
KerryannB Are these results sufficient?
You yeah, thanks
KerryannB Is there anything else on this topic I can find for you today?
You nope, thanks a lot
KerryannB Good luck with your algebra. Have a nice night.
KerryannB Please RATE ME. Thanks for using ChaCha.
Status Session ended.

wanted to test that theory and she didnt bite (although i couldve done more pressing)

OldManWrigley

28-01-2007 21:05:57

Nothing....

I'm about to puke if I read the same thing I've been reading over and over for the last hour, nothing is helping me. Google, nothing. Please?

ilanbg

28-01-2007 21:27:25

That is way too little information for me to figure it out. Sorry mate. (I'm in statistics right now and we're going over this stuff right now, but I'd still at least one extra piece of information.)

Dave82

28-01-2007 21:46:21

[quotea0d1c90460]STAT question quote

im in a first year stats course and theres a question due 2moro for me for an assignment, i think i cant figure it out just because im tired, or im missing some basic concept, but here it is...

Suppose that the distribution of scores on an exam is closely described by a normal curve with mean 100. The 16th percentile of this distribution is 80.

a) what is the 84th percentile.
b) what is the approximate value of the standard deviation of exam scores?
c) what z score is associated with an exam score of 90?
d) what percentile corresponds to an exam score of 140?
e) do you think there were many scores below 40? explain.

i think im just stuck on how to find the standard deviation, the 84th percentile should just be 20 from the max, if its a normal curve, it should start at 0, median of 100, and end at 200, so that means the 84th percentile would be 180...right?

does that mean the standard deviation (50% + 34% = 84%) is 80?

thanks in advance for any help
[/quotea0d1c90460]

i did a search and came up with that, haha, strange.

TFOAF

29-01-2007 09:45:34

G-d damn. I don't remember this. ?

We learned this in Statistics at the beginning of the year. I know there's an equation to find the Standard Deviation though.

Crymson

29-01-2007 10:23:16

Start at the peak in the curve (the mean at 100) and go 1 std. deviation to the left. Since 1 std. dev. is always 34.1% of the total, ur now at the 15.9 (50%-34.1%= roughly 16th) percentile.

Therefore the std. deviation would be the peak (mean) at 100 - 80 (16th percentile) = 20 (distance between, which would be 1u of std. dev.) 8)

OldManWrigley

29-01-2007 12:19:32

[quote138ce0d960="Crymson"]Start at the peak in the curve (the mean at 100) and go 1 std. deviation to the left. Since 1 std. dev. is always 34.1% of the total, ur now at the 15.9 (50%-34.1%= roughly 16th) percentile.

Therefore the std. deviation would be the peak (mean) at 100 - 80 (16th percentile) = 20 (distance between, which would be 1u of std. dev.) 8)[/quote138ce0d960]

You're exactly right. I went into my math class and asked this girl who happens to be really smart and she said the exact same thing.

I think I did fair on the test, but we'll see!

Tsmith10803

29-01-2007 13:09:42

You can also just cross multiply

EDIT
This is easier to understand

http/" alt=""/img245.imageshack.us/img="245/7799/mathuy0.jpg[" alt=""/imgad70f3c59c]

Dave82

29-01-2007 20:15:47

man, i remember doing that stuff though.

Just goes to show garbage in garbage out learning

x323smostwantedx

26-03-2007 23:12:07

Sorry to bump this, but can someone help me with these?

http/" alt=""/img259.imageshack.us/img="259/3514/93696569yd7.png[" alt=""/img0f2b33cae2]
and
[img="0f2b33cae2]http/" alt=""/img408.imageshack.us/img="408/1671/71883472kb3.png[" alt=""/img0f2b33cae2]
THXXXXX

ajasax

26-03-2007 23:51:15

For the 1st one, I got n=1,17/4
Stuck on the 2nd one.

x323smostwantedx

26-03-2007 23:53:03

[quote6f147382f8="ajasax"]For the 1st one, I got n=1,17/4
Stuck on the 2nd one.[/quote6f147382f8]
I got that for the first one also, but then he told me it was only one, so I have to check and show the work. So 1 is not the answer, and I figured 17/4 was, but he said no x .

ajasax

26-03-2007 23:56:16

Well if I check the answers, 1 works, 17/4 doesn't shrug

Wolfeman

26-03-2007 23:58:03

f you and making remember math

Wolfeman

27-03-2007 00:10:41

I got 1 and 17/4 too.

JennyWren

27-03-2007 00:28:53

MAKE SURE YOU DON'T JUST COPY THESE! BE SURE YOU ACTUALLY UNDERSTAND HOW AND WHY THEY WORK!!

http//www.bookwyrm.ca/hostedimages/hw1.gif[" alt=""/img96f2dbe45c]

[img="96f2dbe45c]http//www.bookwyrm.ca/hostedimages/hw2.gif[" alt=""/img96f2dbe45c]

Wolfeman

27-03-2007 00:38:47

Thats so hot Jenny )

x323smostwantedx

27-03-2007 00:41:02

OMG Thank you jenny

http//forum.freeipodguide.com/smilies_mod/upload/5edc2ba05d7e6d2037210ee4bf8668f0.gif[" alt=""/img874a23d9f6]
Ill give u some karma tommorow multiple times
D

TFOAF

27-03-2007 05:23:13

Nice handwriting Jenny. )

x323smostwantedx

28-03-2007 23:21:10

Sorry to bump this again but I have a test tommorow and im confused
Here's the problem

http/" alt=""/img86.imageshack.us/img="86/373/95778190mp4.png[" alt=""/imga4c280faea]

I dont know how to do the rainbow method with square roots. I dont know when to do the rainbow method or when to just drop the square roots once you square them. Can someone do that problem step by step, ill paypal that person 1 dollar. First person gets it.
Is the answer x=6?

Skimboarder

28-03-2007 23:36:08

I'm interested to see the answer and the work. I am not quite to that point in math yet, but it all interests me. In AP Statistics right now.

x323smostwantedx

28-03-2007 23:43:01

[quote4ab75c53f8="Skimboarder"]I'm interested to see the answer and the work. I am not quite to that point in math yet, but it all interests me. In AP Statistics right now.[/quote4ab75c53f8]
AP statistics and u dont know how to do this? This is algebra

tinman5

28-03-2007 23:54:14

x=4, I'm still trying to figure out how to actually do it out step-by-step

x323smostwantedx

28-03-2007 23:56:48

[quote304164a70a="tinman5"]x=4, I'm still trying to figure out how to actually do it out step-by-step[/quote304164a70a]
R u positive?

tinman5

29-03-2007 00:01:21

yes, plug 4 in for x and you'll see it comes out as one, I've got the step-by-step done, I'll put it up in a sec

Daggoth

29-03-2007 00:01:51

Readable handwriting in math. shock

michae229

29-03-2007 00:04:02

why was oldman banned?

x323smostwantedx

29-03-2007 00:06:10

[quote5484a47b96="michae229"]why was oldman banned?[/quote5484a47b96]
He posted a horrible video in the video section, I believe of someone getting their penis chopped off

tinman5

29-03-2007 00:42:53

Here you go, sorry for the wait

http//a29.ac-images.myspacecdn.com/images01/48/l_83ad7406787a91f4a62bafd8bbc53304.jpg[" alt=""/imgee4d94a980]
If you don't understand anything I did please ask

x323smostwantedx

29-03-2007 00:44:33

Awesome, thanks, wats ur paypal?

tinman5

29-03-2007 00:50:14

haha, I forgot you were offering paypal, but it's email==t_inman23@yahoo.comt_inman23@yahoo.com=t_inman23@yahoo.comt_inman23@yahoo.com/email since you ask

x323smostwantedx

29-03-2007 00:51:47

[quote79b840dcc6="tinman5"]haha, I forgot you were offering paypal, but it's email==t_inman23@yahoo.comt_inman23@yahoo.com=t_inman23@yahoo.comt_inman23@yahoo.com/email since you ask[/quote79b840dcc6]
Sent, thanks again

Skimboarder

29-03-2007 11:05:01

[quote2642ceb305="x323smostwantedx"][quote2642ceb305="Skimboarder"]I'm interested to see the answer and the work. I am not quite to that point in math yet, but it all interests me. In AP Statistics right now.[/quote2642ceb305]
AP statistics and u dont know how to do this? This is algebra[/quote2642ceb305]

I see now. I was confused at first, due to the 'rainbow method' or whatever was said. What they did looks like what I would do if I would have gone into the dark.

tinman5

29-03-2007 13:58:34

[quote71e5274e6a="Skimboarder"][quote71e5274e6a="x323smostwantedx"][quote71e5274e6a="Skimboarder"]I'm interested to see the answer and the work. I am not quite to that point in math yet, but it all interests me. In AP Statistics right now.[/quote71e5274e6a]
AP statistics and u dont know how to do this? This is algebra[/quote71e5274e6a]

I see now. I was confused at first, due to the 'rainbow method' or whatever was said. What they did looks like what I would do if I would have gone into the dark.[/quote71e5274e6a]

Yea, "rainbow method" confused me at first also, but I figured that it's just another term for what I learned as the FOIL rule

turpentinedreams

29-03-2007 18:01:58

solution to problem
buy a ti89
type solve((x+5)^(1/2)-x^(1/2)=1,x)
???
profit!

Wolfeman

30-03-2007 11:51:32

You have show your work, sucka!