- var_dump: documentation ( source)
- pow: documentation ( source)
<?php
$frequency = 19;
$resultsCount = 319000;
$result = (pow($frequency/2, 2) / $resultsCount - (pow($frequency/2, 2) / $resultsCount) * ((0 + 0 + 0)*3 /100)) * 100;
var_dump();
var_dump($result);