def mean_riders_for_max_station(ridership):
    """
    Fill in this function to find the station with the maximum riders on the
    first day, then return the mean riders per day for that station. Also
    return the mean ridership overall for comparsion.

    Hint: NumPy's argmax() function might be useful:
    http://docs.scipy.org/doc/numpy/reference/generated/numpy.argmax.html
    """
    overall_mean = ridership.mean()

    max_station = ridership[0, :].argmax()
    mean_for_max = ridership[:, max_station].mean()

    return overall_mean, mean_for_max