def format_time(t):
    """
    Helper function format_time that converts time
    in tenths of seconds into formatted string A:BC.D
    """
    total_seconds = t//10
    minutes = total_seconds//60
    seconds = total_seconds - minutes*60
    tens = t - 10*(minutes*60+seconds)
    
    # %02d format ensures a leading 0 in second count
    out_str = "%d:%02d.%d" % (minutes, seconds, tens)
    
    return out_str