def freq_average(four_month_freq):
    """
    A function that computes the frequency specific average. This is the probability that the ticker
    will only go up in the four months inputed

    :param:     four_month_freq     A series with the historical positive change frequency
    :return:    float               The historical probability that the stock will only go up in 
                                    the input four months
    """
    return ((four_month_freq / 100).product() * 100)