4044.52—Valuation of benefits.
         The plan administrator shall value all benefits as of the valuation date by—
    
    
        
        (a) 
         Using the mortality assumptions prescribed by  § 4044.53 and the interest assumptions prescribed in appendix B to this part;
    
    
    
        
        (c) 
         Using valuation formulas that accord with generally accepted actuarial principles and practices; and