my teacher is foreign so it can be hard to understand wtf she says. and half of the shit she teaches us is online homework oriented so its hard for me to get the jist of wtf is going on.


P(-Zo<Z<0) = .4569


I've tried inverse norm on my ti-83 but that wouldn't work. I have a graph given for all the areas under the curve but those haven't been working either.

I got the problem: P(z<Zo)=.7223 correct, but as soon as you have Z between random variables I get confused on how to do it.


The "<" signs are supposed to be greater than or equal to

can you explain what you're actually solving?

it's been almost a decade since i did stats lol. P for z between two constants is just the area between the two constants right? if so, then P = (area between zo and 0 for negative zo) = (area between -infinity and 0) - (area between - infinity and Zo). pretty sure your calculator will do those two pieces, so just subtract em to get the area

/edit: oh, are you trying to find the value Zo? same idea. it's basically the two areas. and since you know one of the constraints (eg: 0) then you know one of the two areas. since you know P and one of the areas, you can solve for the other area. then look up the corresponding z value for that area. if memory serves, area between -infinity and 0 is .50. so the area you're looking for is .0431. going by the 68 95 99.7 rule, that would make Z0 somewhere between -1 and -2

This post was edited by carteblanche on Jul 21 2013 03:00pm

Look up the normal probability distribution table. On each side of Z=0, is p=0.5. Also P(-Zo<Z<0) is the same as P(Zo>Z>0).
Hope that helps

Ok, what you're looking for here is the probability Z is between -Z0 and 0. To find this, find the probability Z is less than 0, then find the probability Z is less than Z0.

Take P(Z<0) - P(Z< -Z0)


Therefore, P(Z<0) - P(Z < -Z0) = P(-Z0 < Z < 0) = .4569


So what exactly is given and what are you solving for? What I've given you should be enough to solve the problem, but if you're still confused please specify further so I can help

Also, Exx speaks the truth! Normal curves are symmetric around 0, so you can calculate this either way