STAT 171 ppl (1 Viewer)

[jake2.0]

Hey guys, any of you do Stat 171? Prolly anyone in first year actuarial. I just have a really simple question to ask from the 2004 paper, the first one actually, lol;

"For a normally distributed random variable, what proportion of value are within 1.5 standard deviations of the mean?"

thx

 

[robbo_145]

You just need to use your Z tables
P (Z < |1.5|) = 1- P (Z > |1.5|)
= 1 - 2*0.0668
=0.8664

any other probs ill be on msn most of tonight.
<---- just click that little guy

 

[jake2.0]

You just need to use your Z tables
P (Z < |1.5|) = 1- P (Z > |1.5|)
= 1 - 2*0.0668
=0.8664

any other probs ill be on msn most of tonight.
<---- just click that little guy

Thanks for that, damn iam so screwed tomorrow . Are you part of the central coast group who always sit up the back in the lectures?

 

[redruM]

This won't really answer your question directly, but hopefully it will give you a better idea of the concept.

(see attatched)

You need to find the area enclosed between -1.5 and 1.5 (purple lined). Now, your tables won't have that specific area, they might give you the blue shaded area (one or two sides). Now, if you can work out the blue area, you can just use the following properties to calculate the purple bit:

The total area is equal to 1.0, and
The area is equally distributed (either side of 0, the area is equal to 0.5)

Once you work out the blue area, you just use a bit of common sense to work out what you need.




Just another point, P (Z < |1.5|) = P (Z < 1.5) + P (Z > -1.5). Then you can think of finding those two areas.



I am sure you knew most of this stuff, I was just bored. So don't take offence if it sounds like I mean to make you look like a tool or whatever.

Good luck for STAT171, hope you get your Cr.

 

[jake2.0]

Its cool i got it now, i thought that it was .75 st deviations from the mean on one side and another .75 on the other, so a total of 1.5 ( silly me )

Yeah ill need that luck, sure dont wanna do all this again. Thats my motivation.

 

[robbo_145]

Are you part of the central coast group who always sit up the back in the lectures?

yerp I'm one of them

 

[ND]

Just another point, P (Z < |1.5|) = P (Z < 1.5) + P (Z > -1.5). Then you can think of finding those two areas.

That should read:

P(Z<|1.5|) = P(Z<1.5) - P(Z<-1.5).

I'm sure you know this and it was just a typo, but i just thought i'd correct it so the original poster doesn't get confused. (plus it's a welcome distraction from ACST356 cramming!!)

 

[redruM]

Bah!

How embarrassment.

I guess I was just trying to show how to think about those things...


/actuarial wannabe