Maths- Gym for Brainiacs

Only Spanky can solve it?

kiranr wrote:
Only Spanky can solve it?

Everybody is free to solve it

Is the distance traveled by Alaba an inverse exponential function?

kiranr wrote:
Is the distance traveled by Alaba an inverse exponential function?

I don't know. I haven't solved the question, yet. The question is just an idea how it should work but I'm sure it's solvable, theoretically
It's up to you how to solve this

How the hell do you come up with these questions?

beatrixasdfghjk. wrote:How the hell do you come up with these questions?

Exercise books or some theoretical background where I fit a question frame around it. Alaba question is one from theoretical backgorund. Basically, a curve meets a straight line

Okay, what I'm trying at the moment: you let theta be a tiny, tiny angle, such that tan theta = x/35, where x is the distance the dog travelled?
Then tan (theta+phi) = (x+h-vert guy has travelled since)/(35-horiz guy has travelled since). Where every pronumeral is just a tiny, tiny amount.

I can't be bothered writing out exactly what I got, it's too complicated for here .__.
DOES THAT SOUND GOOD? *has no idea*

If x and h are both tiny amounts, can I just use like 2x instead of x+h?

Oh, it's getting far too complex for me .

beatrixasdfghjk. wrote:Okay, what I'm trying at the moment: you let theta be a tiny, tiny angle, such that tan theta = x/35, where x is the distance the dog travelled?
Then tan (theta+phi) = (x+h-vert guy has travelled since)/(35-horiz guy has travelled since). Where every pronumeral is just a tiny, tiny amount.

I can't be bothered writing out exactly what I got, it's too complicated for here .__.
DOES THAT SOUND GOOD? *has no idea*

I seriously don't get what you were doing If you chose an angle, which one? What is phi?
Also, I solved this one without the use of trigonometry. Spanky and kiranr, you guys alive?

Immortal Babun wrote:
I seriously don't get what you were doing If you chose an angle, which one? What is phi?
Aslo, I solved this one without the use of trigonometry. Spanky and kiranr, you guys alive?

Well, i got started and i figured the path followed by Alaba should be a function of x which is the path followed by Shtuppid. And at x = 0, f(x) = 35.

And i thought it should be an inverse curve of the second order, so the second derivative should be a constant...

f''(x) = a.

But stopped here, because dont know if i am going in the right direction..

kiranr wrote:

Immortal Babun wrote:
I seriously don't get what you were doing If you chose an angle, which one? What is phi?
Aslo, I solved this one without the use of trigonometry. Spanky and kiranr, you guys alive?

Well, i got started and i figured the path followed by Alaba should be a function of x which is the path followed by Shtuppid. And at x = 0, f(x) = 35.

And i thought it should be an inverse curve of the second order, so the second derivative should be a constant...

f''(x) = a.

But stopped here, because dont know if i am going in the right direction..

I used isomery towards polygonal line to solve this question which is quite similar to your approach. It might work

Immortal Babun wrote:

kiranr wrote:

Immortal Babun wrote:
I seriously don't get what you were doing If you chose an angle, which one? What is phi?
Aslo, I solved this one without the use of trigonometry. Spanky and kiranr, you guys alive?

Well, i got started and i figured the path followed by Alaba should be a function of x which is the path followed by Shtuppid. And at x = 0, f(x) = 35.

And i thought it should be an inverse curve of the second order, so the second derivative should be a constant...

f''(x) = a.

But stopped here, because dont know if i am going in the right direction..

I used isomery towards polygonal line to solve this question which is quite similar to your approach. It might work

.
I have no idea what you're talking about .
Really, middle school? .

i feel bad doing this again but im stuck with stats again and i cant find anything on the net, sorry

So im doing hypothisis testing for a sample of 200 scores, ive got mu=$260 from null hypoth, n=200 and ive set alpha to 5% although i havent got population varriance because the data im given is a sample

Although am i right in thinking thinking that by the Central Limit Theory i should be able to substitiute the sample varriance in place of the population varriance because its an unbiased estimator of the pop. varriance? because i cant see a way i can find an exact value of the pop. varriance

although because ive already evoked the CLT once because the data im testing is non-normally distributed would it change my overall forumla to use it twice or would i still use

P(Z<(X-mu)/(sigma/sq root of n))=alpha

to find the Z-score that marks the "cut off region" in a standardised set

and then my second question is because i have 200 scores to test, would i just say how many of the 200 scores would lead to accepting the null and how many would lead ot rejecting the null and thne go with the majority or could i just find the average of the scores and test that single score against the null?


thanks

fatman123 wrote:i feel bad doing this again but im stuck with stats again and i cant find anything on the net, sorry

So im doing hypothisis testing for a sample of 200 scores, ive got mu=$260 from null hypoth, n=200 and ive set alpha to 5% although i havent got population varriance because the data im given is a sample

Although am i right in thinking thinking that by the Central Limit Theory i should be able to substitiute the sample varriance in place of the population varriance because its an unbiased estimator of the pop. varriance? because i cant see a way i can find an exact value of the pop. varriance

although because ive already evoked the CLT once because the data im testing is non-normally distributed would it change my overall forumla to use it twice or would i still use

P(Z<(X-mu)/(sigma/sq root of n))=alpha

to find the Z-score that marks the "cut off region" in a standardised set

and then my second question is because i have 200 scores to test, would i just say how many of the 200 scores would lead to accepting the null and how many would lead ot rejecting the null and thne go with the majority or could i just find the average of the scores and test that single score against the null?


thanks

What do mean by you got mu = 260 from null hypothesis? Did you calculate the mu from the sample and then tested the null hypothesis?

fatman123 wrote:i feel bad doing this again but im stuck with stats again and i cant find anything on the net, sorry

So im doing hypothisis testing for a sample of 200 scores, ive got mu=$260 from null hypoth, n=200 and ive set alpha to 5% although i havent got population varriance because the data im given is a sample

Although am i right in thinking thinking that by the Central Limit Theory i should be able to substitiute the sample varriance in place of the population varriance because its an unbiased estimator of the pop. varriance? because i cant see a way i can find an exact value of the pop. varriance

although because ive already evoked the CLT once because the data im testing is non-normally distributed would it change my overall forumla to use it twice or would i still use

P(Z<(X-mu)/(sigma/sq root of n))=alpha

to find the Z-score that marks the "cut off region" in a standardised set

and then my second question is because i have 200 scores to test, would i just say how many of the 200 scores would lead to accepting the null and how many would lead ot rejecting the null and thne go with the majority or could i just find the average of the scores and test that single score against the null?


thanks

Either my English deceived me or you wrote something incoherently :vagi:

my understanding of stats isnt great and because i dont have the assumed knowledge for the course my fondations arent great so i just sort of wrote it in a way i understand

anyway it doesnt really matter now because ive got to do that population proportion thing from a binomial distribution (dont worry i dont know what it is either) so ill just follow the slides and it should be ok, thanks for trying to help anyway babun and kiranr

if im doing a hypothesis test and i set my confidence intervals to a Z-score of 1.96 and the standardised value of the sample mean is -6.85 then my P-value would be the probability of a score being more extreme then -6.85 which would be 0, right?

fatman123 wrote:if im doing a hypothesis test and i set my confidence intervals to a Z-score of 1.96 and the standardised value of the sample mean is -6.85 then my P-value would be the probability of a score being more extreme then -6.85 which would be 0, right?

Write the formula and everything related to your question

Babun, ever going to explain that dog question?
In simple terms for someone who's never heard of isometrics before .

Thread turning into a 'fatman homework thread' .

Immortal Babun wrote:

fatman123 wrote:if im doing a hypothesis test and i set my confidence intervals to a Z-score of 1.96 and the standardised value of the sample mean is -6.85 then my P-value would be the probability of a score being more extreme then -6.85 which would be 0, right?

Write the formula and everything related to your question

H0: µ=$260
H1: µ<$260
alpha=5%
µ=$260
sigma≈S=49.90718
n=200
X̅=$235.81

X̅~N(260,49.90718^2/200)

P(Z< (x-μ) on s over sqrt of n)

P(Z<(x-260) on 49.90718/sqrt of 200)

Z<-1.96

The rejection region can be defined with a Z-score of ±1.96


Z=(X̅-μ) over sigma on sqrt of n

Z=(235.81-260)/(49.90718/sqrt 200)

Z=-6.85

Reject the null hypothesis in favour of the alternative

p-value=P(Z<-6.85)
=0.5 (my tables are for values 0<Z<infinity so i get 0.5 for -6.85 by symmetry)
=0.5-0.5
p-value=0



So pretty much thats my hypothesis testsorry that ive had to se things like "over" and "sqrt" but i dont know how to write fractions etc here, although since ive asked that question im pretty sure finding the p-value is inapporpriate to this situation anyway because i think its only worth finding of you accept the null, but i dunno

thanks Babun

beatrixasdfghjk. wrote:Babun, ever going to explain that dog question?
In simple terms for someone who's never heard of isometrics before .

Thread turning into a 'fatman homework thread' .

thank god this is for an assignment not homework, if i struggld this much with homework id be in big trouble. sorry for asking for so much help but im mathematically illiterate and this business stats course is really tough and i guess it doent help that i dont have the assumed knowledge for the class (i did the lowest level of math in high school)

still the assignment is due thursday, so once thats done i just need to pass the final and ill never have to do stats again!!! (i hope)

and to be fair, ive lurked this thread for a while before i posted in it, its just that i dont know the answer to anything here so ive had nothing to say untill i started asking for help :S

forget that other question, im pretty sure thats all right as it agrees with all my descriptive statistics but ive just no idea how to do population proportion, and it doesnt help that the lecture slides are purposley brief to force people to go to lectures and yet i go to all of them and i still dont get it
anyway the question that all this comes from is of the businesses key performance indicators that reads "more then 50% of customers stay for a full week (ie 7 nights)



EDIT:0.28 is between -1.96 and 1.96 so im accepting the null thats actually terrible by me, sorry

so my reasoning to accept the null was that when i was forming the confidence interval of 0.44,0.58 i found a z-score of 1.96 and then in the next formula (i think) i found the Z-score of the population proportion, P hat (0.28). But i dont know if thats right, could i use this formula instead (would have sub in different numbers) to find the Z-score fo P hat that way to accept/reject the null? or is that only for hypothesis testing? but then this is a hypothesis test but then its a poplation proportion thing too :S



or should i just conclude that in 95% of samples (from alpha=0.05) between 44% and .58% of customers will spend 7 nights at the resort and thus the business acheives is key performance indicator in most cases?

thanks for the help Babun and everyone, i really appreciate it <3

fatman123 wrote:forget that other question, im pretty sure thats all right as it agrees with all my descriptive statistics but ive just no idea how to do population proportion, and it doesnt help that the lecture slides are purposley brief to force people to go to lectures and yet i go to all of them and i still dont get it
anyway the question that all this comes from is of the businesses key performance indicators that reads "more then 50% of customers stay for a full week (ie 7 nights)



EDIT:0.28 is between -1.96 and 1.96 so im accepting the null thats actually terrible by me, sorry

so my reasoning to accept the null was that when i was forming the confidence interval of 0.44,0.58 i found a z-score of 1.96 and then in the next formula (i think) i found the Z-score of the population proportion, P hat (0.28). But i dont know if thats right, could i use this formula instead (would have sub in different numbers) to find the Z-score fo P hat that way to accept/reject the null? or is that only for hypothesis testing? but then this is a hypothesis test but then its a poplation proportion thing too :S



or should i just conclude that in 95% of samples (from alpha=0.05) between 44% and .58% of customers will spend 7 nights at the resort and thus the business acheives is key performance indicator in most cases?

thanks for the help Babun and everyone, i really appreciate it <3

Sorry for late response, I'm really busy
Interestingly enough, I pmed you about confidence intervals earlier but you thought you wouldn't need it :lol!:

About the the questions ( red part marked) :

1. It's alright.
2. You define yourself how accurate your confidence interval should be. For a tourismus resort, 95% is more than enough. You could never be 100% sure though. That's why it's called hypothesis testing

Immortal Babun wrote:Sorry for late response, I'm really busy
Interestingly enough, I pmed you about confidence intervals earlier but you thought you wouldn't need it :lol!:

About the the questions ( red part marked) :

1. It's alright.
2. You define yourself how accurate your confidence interval should be. For a tourismus resort, 95% is more than enough. You could never be 100% sure though. That's why it's called hypothesis testing

yeah i remember that now that you mention, at the time i ddint realise how hard this course was going to be :S
im going to have another look at it now actually

i ended up having a few words spare when i finished my report so i put both the bits you put in red because it sounds nice and i just wanted to cover all bases

anyway im just printing it off now and im handing it in tomorrow, so thanks for all the help everyone, i really do appreciate it

lol the wiki article you linked me was the one i used to supplement the lecture slides, i guess you really did know what was coming up