The average 70 kg (150 lb) being has 5.5 L of blood (1.05 g/mL). How many 1 oz drinks of 20% alcohol by volume (40 proof) must be consumed for the blood alcohol content (BAC) to exceed 0.1 (BAC is g alcohol per 100 mL blood) ? Assume that all of the alcohol consumed goes directly into the blood.

The total blood given is 5.5 liters

Thus, total alcohol needed for BAC (blood alcohol content) to exceed 0.1 gram per 100 ml will be 0.1/100 * 5500 = 5.5 grams alcohol.

1 oz = 28.3 grams

28.3 gram water = 28.3 ml

It has 20 percent alcohol by volume,

Therefore, alcohol in one drink will be:

20/100 * 28.3

= 5.66 ml

= 5.66 * 0.79 (density of ethanol)

= 4.47 gram

Thus, no of drinks will be 5.5 g / 4.47 g = 1.2

Hence, 1.2 drinks will make the BAC to exceed 0.1 g / 100 ml in the blood.