Total mass of mouthwash = volumedensity
1 pint is 568.261 mL therefore 1.040 pints = 591.0 mL (4 significant figures)
Therefore mouthwash mass in a bottle = 591.0 mL 0.851 g/mL = 503 g (3 s.f.)
In 160 bottles, ethanol mass = 509 g 160 0.381 = 30700 g = 30.7 kg