def to_nom_val_and_std_dev(interval):
    """
    For a given interval [mu - sigma, mu + sigma] returns (mu, sigma)
    (Here mu is nominal value and sigma is standard deviation)

    Parameters
    ----------
    interval: ~list [lwr_bnd, upr_bnd]

    Returns: ~tuple

    """
    lwr_bnd, upr_bnd = interval
    sigma = (upr_bnd - lwr_bnd)/2
    mu = lwr_bnd + sigma
    return (mu, sigma)