def student_ranking(student_scores, student_names):
    """Organize the student's rank, name, and grade information in ascending order.

    :param student_scores: list - of scores in descending order.
    :param student_names: list - of string names by exam score in descending order.
    :return: list - of strings in format ["<rank>. <student name>: <score>"].
    """

    results = []
    for index, name in enumerate(student_names):
        rank_string = str(index + 1) + ". " + name + ": " + str(student_scores[index])
        results.append(rank_string)

    return results