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<h1>ZTEST Function</h1>
<p>The <b>ZTEST</b> function is one of the statistical functions. It is used to return the one-tailed probability-value of a z-test. For a given hypothesized population mean, μ0, <b>ZTEST</b> returns the probability that the sample mean would be greater than the average of observations in the data set (array) — that is, the observed sample mean.</p>
<p>The <b>ZTEST</b> function syntax is:</p>
<p style="text-indent: 150px;"><b><em>ZTEST(array, x [, sigma])</em></b></p>
<p><em>where</em></p>
<p style="text-indent: 50px;"><b><em>array</em></b> is the range of numeric values against which to test <b><em>x</em></b>.</p>
<p style="text-indent: 50px;"><b><em>x</em></b> is the value to test.</p>
<p style="text-indent: 50px;"><b><em>sigma</em></b> is a population standard deviation. This is an optional argument. If it is omitted, the sample standard deviation is used.</p>
<p>The values can be entered manually or included into the cell you make reference to.</p>
<p>To apply the <b>ZTEST</b> function,</p>
<ol>
<li>select the cell where you wish to display the result,</li>
<li>click the <b>Insert function</b> <img alt="Insert function icon" src="../images/insertfunction.png" /> icon situated at the top toolbar,
<br />or right-click within a selected cell and select the <b>Insert Function</b> option from the menu,
<br />or click the <img alt="Function icon" src="../images/function.png" /> icon situated at the formula bar,
</li>
<li>select the <b>Statistical</b> function group from the list,</li>
<li>click the <b>ZTEST</b> function,</li>
<li>enter the required arguments separating by commas or select a range of cells with the mouse,</li>
<li>press the <b>Enter</b> button.</li>
</ol>
<p>The result will be displayed in the selected cell.</p>
<p style="text-indent: 150px;"><img alt="ZTEST Function" src="../images/ztest.png" /></p>
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