Question 1033448
<pre>
Yes, it's asking for two z-scores, the left one will be
negative and the right one positive.  They will have the
same absolute value, since the normal curve is symmetrical
about the y-axis.

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The middle 0.80 of the normal curve has 0.10 to the left of it
and 0.10 to the right of it.

If  you have a TI-83 or TI-84 calculator,

2ND VARS 3 for invNorm(.1,0,1) ENTER

Read z = -1.281551567, and by symmetry 
the upper z-score is +1.281551567

Maybe you're supposed to use a normal table.

There are two kinds of normal tables in use today.

If you are using a table that has negative z values,
look in the body of the table for the closest value
to 0.10 which is 0.1003 and it occurs where z=-1.28.

If you are using a table that reads from the middle,
then look in the body of the table for the closest
value to 0.40 (one half of 0.80), which is 0.3997, and
it occurs where z=1.28.

Edwin</pre>