Amouthwash is 38.1% ethanol by mass. if each bottle contains 1.040 pints of mouthwash with a density of 0.851 g/ml, how many kilograms of ethanol are in 160 bottles of the mouthwash

Total mass of mouthwash = volume*density
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

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .