def calc_db_cost_v3(db) -> float:
    """Returns a noise cost for given dB: every 10 dB increase doubles the cost (dB >= 45 & dB <= 75).
    """
    if db <= 44:
        return 0.0
    db_cost = pow(10, (0.3 * db)/10)
    return round(db_cost / 100, 3)