I havent taken precalc in like 3 or4 years and now Im in statistics.

I know this shit cant be that hard but Im freggin stumped right now. Book makes no sense.

Working with continuous random variables:

How do you determine the median and the quartiles for the probability distribution in the following:



I know you can tell from looking at the pic, but what are the equations used?

10/3/2008 1:16:36 AM

since it's a uniform distribution, the median (50th percentile) will be half the length of f(x)

[Edited on October 3, 2008 at 11:02 AM. Reason : similarly with the quartiles]

10/3/2008 11:02:06 AM

^that's the common sense method. he wants to actually use the formula. can't remember what they are.

10/3/2008 11:27:21 AM

There really is no formula. Look at the picture and go, okay the upper %75 is (3/4)*2 = 3/2. Same for the bottom 25% and middle 50%.

10/3/2008 11:40:44 AM

Well thats how I calculated it in my mind, I was just thinking there had to be something more complicated than that from the question.

Eh...

10/3/2008 12:23:01 PM

well, there is, but it involves calculus

10/3/2008 1:53:21 PM

yea - he told us that in lecture but its something that is out of the scope of this class.

I guess it didnt help when he spends most of the time proving the equations and tries to tell us how to use them in the last 5 mins of class.

fail.


NEXT QUESTION

How would you find the 15th percentile of a curve in the graph of a triangle?

 
   /
  / |
 /  | 
/   |

10/3/2008 2:05:56 PM

use the formula for the area of a triangle, set it equal to 0.15
use f(x) to find the length of the base and height in terms of x
plug it in to the area equation and solve

10/3/2008 3:06:58 PM