<?php

    function harmonicMeanV2()
    {
    	$arguments = func_get_args();
    	$arguments = array_map('pow', $arguments, array_fill(0, count($arguments), -1));
    
    	return count($arguments) / array_sum($arguments);
    }

var_dump(harmonicMeanV2(40, 60), 48.0);

float(48)
float(48)