private function calculateEsiPerApplicant(Collection $applicants): float 	{ 		$filteredApplicants = $this->filterEsiApplicableApplicants($applicants);  		$totalEsiScore = 0;  		$filteredApplicants->each(function ($applicant) use (&$totalEsiScore) { 			$applicantEsiQuestionSum = $applicant->esi_workplace_satisfaction + $applicant->esi_workplace_expectations + $applicant->esi_ideal_job_comparison; 			$totalEsiScore += $this->esiFormula($applicantEsiQuestionSum); 		});  		return $filteredApplicants->isNotEmpty() ? $totalEsiScore / $filteredApplicants->count() : 0; 	}