def calc_duration(chromosome, video_lengths):
    """Calculates the duration of the set of videos when combined
    Parameters
    ----------
    chromosome : np.ndarray
        Dummy-coded chromosome of videos
    video_lengths : np.ndarray
        Lenghts (in seconds) of each video
    Returns
    -------
    int
        Length of set of videos
    """
    return sum(chromosome*video_lengths)