<PRE><B>Question 1155616</B>
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Use a t table such as this one
&lt;a href = &quot;http://www.ttable.org/&quot;&gt;http://www.ttable.org/&lt;/a&gt;
which can be found in the back of statistics textbooks. At the bottom of the table, it shows 99% confidence interval. Highlight the entire column. Then highlight the entire row with df = 19, where df stands for &quot;degrees of freedom&quot;


This diagram shows what I mean
&lt;img width=&quot;75%&quot; src = &quot;https://i.imgur.com/P4YKToB.png&quot;&gt;


The row and column intersect at the value 2.861
This means, P( -2.861 &lt; T &lt; 2.861 ) = 0.99


Answer: &lt;font color=red&gt;2.861&lt;/font&gt; 
This value is approximate
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