What is the formula for figuring out the alcohol percentage in a person's body?A 40 year old manager, at a prominent legal firm in L.A., experiences abdominal pain post lunch.  He goes to the...

What is the formula for figuring out the alcohol percentage in a person's body?

A 40 year old manager, at a prominent legal firm in L.A., experiences abdominal pain post lunch.  He goes to the restroom a couple of times, but continues to experience pain and cramps.  He eventually decides to get himself examined.  While questioning him, you learn that he consumed two bottles of beer at lunch.  The alcohol (ethyl alcohol/ethanol) content in a 12 oz. bottle of beer is 5%.  The man's weight is 150 pounds and he was drinking over an hour period. 

Calculate the pecentage of alcohol in the patient's body.

Asked on by deekoch

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bandmanjoe's profile pic

bandmanjoe | Middle School Teacher | (Level 2) Senior Educator

Posted on

To calculate the blood alcohol level of an individual, you would start with .038 for a 100 pound person as a starting point.  For every additional 10 pounds, you would subtract .002 to .003, as this would lower the percentage of alcohol within the body.  A 150 pound person would have a blood alcohol level of .025 after just one drink.  The person in this question had two drinks, so 2 x .025 = .05.

The next thing we do is add the number of drinks together:1 + 1 = 2

Subtract the number of hours since the person had their last drink, which in this case would be 1:  2 -1 = 1

Multiply by .015:  1 x .015 = .015 (.015 is the amount of alcohol the liver processes per hour).

Subtract this number from the original blood alcohol concentration:

.05 - .015 = .035, BAC

It should be noted that each individual has differences in body makeup, fat percentage versus lean muscle mass percentage.  Sex makes a difference as well, males tend to have 58% more water in their bodies as opposed to 49% in females. 

Sources:

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