Question 1002834
<pre>
The reason the normal table only goes up to z=3.4 is because
the area under the normal curve to the right of 3.4 and to
the left of -3.4 is so small that it is negligible, and for all
practical statistical purposes is equal to zero.

So the area to the left of -4.4721 is for all practical statistical
purposes is 0, and thus the area to the left is 0.  Practically 
all the area to the left of it is included.  Notice on the graph of 
the normal curve that the two green lines show where -4.4721 and 
4.4721 are located. The red lines are at 3.4 and -3.4. They show why 
there is no use for tables to include z-scores beyond them, since the 
area beyond them is so small.

{{{drawing(400,200,-5,5,-.5,1.5, graph(400,200,-5,5,-.5,1.5, exp(-x^2/2)), 
red(line(-3.4,0,-3.4,.5),line(3.4,0,3.4,.5)), 
green(line(-4.4721,0,-4.4721,.5),line(4.4721,0,4.4721,.5)),locate(4.8,-.01,z),locate(4.8,.2,z)
  
)}}}

Edwin</pre>