SOLUTION: what is the area under the curve between z=1.50 and z=2.50?

There are two kinds of normal z-tables around these days. The
most common type gives areas from the middle z=0 to the right 
and others give the area from the extreme left to the right.

I will assume first that you have the first type, that reads 
from z=0 to the right.  I'll explain below what to do if you
have the other type as well as how to find it on a TI-83 or 
TI-84 graphing calculator.  


 =  — 
AREA BETWEEN z=1.5 & z=2.5 = AREA BETWEEN z=0 & z=2.5  —  AREA BETWEEN z=0 & z=1.5 

If you have a table which gives the area between 
z=0 and z="whatever",

AREA BETWEEN z=0 and z=2.50 is given in the table as .4938
AREA BETWEEN z=0 and z=1.50 is given in the table as .4332

therefore:

AREA BETWEEN z=1.5 & z=2.5 = .4938 — .4332 = .0606

If you have the other kind of table those values will 
be .9938-.9332=.0606, the same answer.

If you have a TI-83 or TI-84 calculator and your teacher will
let you use it,
 
From the cleared main screen
 
Press 2ND
Press VARS
Press 3
 
you will see this on the screen -->  invNorm(
 
after that type 1.5,2.5) so that you see this on the
screen --->  invNorm(1.5,2.5)
 
[If you can't find the comma key it is the key just to
the right of the x2 key].
 
Press ENTER
 
You will see .0605975489, which rounds to the value .0606

Edwin