def other_correct_rate
    if school.present?
      general_answer_count = general_statistics.answers_count
      general_correct_count = general_statistics.correct_count

      other_answer_count =  general_answer_count - answers_count
      other_correct_count = general_correct_count - correct_count

      (other_correct_count/other_answer_count.to_f)*100
    else
      nil
    end
  end

  def general_statistics
    self.class.where(mock_id: mock_id, mock_question_id: mock_question_id, school_id: nil).first
  end