<PRE><B>Question 1162324</B>
&lt;pre&gt;

On your TI-84 calculator,

Press stat, then the right arrow key twice to highlight TESTS

press enter

See this, and type in these values

         Z-Test
Inpt:Data Stats    &lt;--highlight Stats
µ&lt;sub&gt;0&lt;/sub&gt;:20
x̄:18.75
n:80
µ:≠ &lt;µ&lt;sub&gt;0&lt;/sub&gt; &gt;µ&lt;sub&gt;0&lt;/sub&gt;    &lt;--highlight &lt;µ&lt;sub&gt;0&lt;/sub&gt;    
Color:  BLUE
Calculate Draw       &lt;--highlight Calculate

µ&lt;20
z=-2.484519975
p=0.0064863228        &lt;--THE ANSWER 
x̄:18.75
n=80

Edwin&lt;/pre&gt;   
</PRE>