I calculated my z value to be z=(23-18)/3 = 5/3 = 1.66

I am trying to find P(Z>1.6666) = ?

can someone please explain how to get this probability using the Z table?

thanks in advance

i got 0.0485

0.5 - 0.4515

Printable View

- Dec 1st 2008, 10:46 AMndcruzZ problem
I calculated my z value to be z=(23-18)/3 = 5/3 = 1.66

I am trying to find P(Z>1.6666) = ?

can someone please explain how to get this probability using the Z table?

thanks in advance

i got 0.0485

0.5 - 0.4515 - Dec 1st 2008, 11:01 AMMoo
Hello,

Well, if this is what you got by using the Z table, then you know how to use it, because your answer is correct... :p

The z table represents the area bounded by the Gaussian curve, the x axis, the y axis and the line x=a, where a is the z value of the table.

So in fact, tables give you this probability : $\displaystyle P(0<z<a)$

Let a>0 and b<0. Let $\displaystyle z_a$ and $\displaystyle z_b$ be the z scores of a and b.

$\displaystyle P(z<a)=0.5+z_a$

$\displaystyle P(z>a)=0.5-z_a$

$\displaystyle P(z>b)=0.5+z_b$

$\displaystyle P(z<b)=0.5-z_b$