public function calculateClientSurveyFinalGrade(ClientSurvey $client_survey, Collection $answers): string 	{ 		$average_score = collect();  		foreach ($client_survey->survey->categories as $category) { 			$category_answers = $answers->where('question.category_id', $category->getKey());  			$category_score = number_format($category_answers->avg('answer_value'), 3, '.', '');  			$average_score->push($category_score); 		}  		return number_format($average_score->avg(), 3); 	}