My Math Forum  

Go Back   My Math Forum > College Math Forum > Advanced Statistics

Advanced Statistics Advanced Probability and Statistics Math Forum


Reply
 
LinkBack Thread Tools Display Modes
May 13th, 2012, 05:46 AM   #1
Newbie
 
Joined: May 2011

Posts: 28
Thanks: 0

probablity in interval

Hello,

Could you help me with this:
Four speedmeters measured these values: 191, 199, 196 and 194 km/h. Standart deviation is 2 km/h (we can consider normal distribution). There are no errors in the measurements. What is the probability that speed is in interval (193, 195) ?

thanks
token22 is offline  
 
May 13th, 2012, 09:16 AM   #2
Member
 
Joined: Nov 2009

Posts: 90
Thanks: 0

Re: probablity in interval

Hello token22,

According to this video lecture, the standard error of the mean (SEM) is 1/2.
http://www.youtube.com/watch?v=J1twbrHel3o

So 193 is 4 SEM from the sample mean. Using another video lecture as guidance, this should make your probability close to (just a tiny bit smaller than) 50%.
http://www.youtube.com/watch?v=bekNKJoxYbQ

Now you're gonna have to confirm this, because I'm quite sloppy. Let us know how it goes.
Aqil is offline  
May 13th, 2012, 12:21 PM   #3
Newbie
 
Joined: May 2011

Posts: 28
Thanks: 0

Re: probablity in interval

Oh i forgot to those youtube demonstration videos, anyway I got 0,4772 by video you sent, so it could be fine.
token22 is offline  
May 13th, 2012, 01:52 PM   #4
Member
 
Joined: Nov 2009

Posts: 90
Thanks: 0

Re: probablity in interval

Oh, that's right. SEM = s/(n^.5) = 2/(4^.5) = 1
So 0.4772 is right.

Yeah, Mr Khan is awesome!
Aqil is offline  
Reply

  My Math Forum > College Math Forum > Advanced Statistics

Tags
interval, probablity



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Probablity DenmansDinner Algebra 0 January 17th, 2012 09:13 PM
Calculate probablity neo Algebra 3 December 16th, 2011 09:14 PM
Probablity !!!! Confusing daivinhtran Algebra 4 June 11th, 2011 11:49 PM
PRobablity daivinhtran Algebra 4 June 11th, 2011 07:52 PM
PRobablity daivinhtran Algebra 1 June 11th, 2011 07:07 PM





Copyright © 2019 My Math Forum. All rights reserved.