1. ## Normal Distribution question

Hi
Can someone help me on the following questions:
Determine the value of z in the following case: Pr(-z<Z<z)=0.954

I done InvNorm(0.954,0,1) but this is incorrect

Find the quartiles of the standard normal distribution?

P.S

2. ## Re: Normal Distribution question

first find the $\displaystyle \textrm{P}(Z<z)$

it will be equal to $\displaystyle \frac{0.954}{2}+0.5=0.977$

so find z according to that value from the data sheet

3. ## Re: Normal Distribution question

first find the $\displaystyle \textrm{P}(Z<z)$

it will be equal to $\displaystyle \frac{0.954}{2}+0.5=0.977$
why do you have to plus 0.5 after halving 0.954?

4. ## Re: Normal Distribution question

because normally on datasheets, $\displaystyle \textrm{P}(Z<z)$ is given,

so after halving 0.954 you'll get $\displaystyle \textrm{P}(0<Z<z)$. In order to get the above value you should add 0.5 (because the graph is symmetrical around P(z) axis)

5. ## Re: Normal Distribution question

How would i find the quartiles of the standard normal distribution?

i know that there it is split into three sections, but how do i calculate the percentages

6. ## Re: Normal Distribution question

Originally Posted by Paymemoney
How would i find the quartiles of the standard normal distribution?

i know that there it is split into three sections, but how do i calculate the percentages
Rview the definition of a quartile. Then apply what you learned so far in this thread.