Short Answer 
To calculate the Blood Alcohol Concentration (BAC), first determine total alcohol consumed from drinks (42 grams), convert body weight into grams (63560 grams for 140 lbs), and apply the gender constant (0.68 for men) to find adjusted weight (43220.8 grams). Calculate initial BAC (0.0972), convert to percentage, and adjust for metabolism over time resulting in an estimated BAC of approximately 0.08.
Step 1: Calculate the Total Alcohol Consumption
Start by determining the total amount of alcohol consumed. In the U.S., a standard drink contains 14 grams of alcohol. If the individual has 2 beers and 1 shot, the total number of standard drinks is:
- 2 beers + 1 shot = 3 standard drinks
- 3 standard drinks x 14 g = 42 grams of alcohol
Step 2: Convert Weight and Apply Gender Constant
The next step is to convert the body weight from pounds to grams and then apply the gender constant. To do this:
- Convert weight: 140 lbs x 454 = 63560 grams
- Use the gender constant for men, which is 0.68.
- Calculate adjusted grams: 63560 g x 0.68 = 43220.8
Step 3: Calculate BAC and Adjust for Time Passed
Now that you have both the total alcohol and adjusted weight, you can calculate the Blood Alcohol Concentration (BAC). Follow these steps:
- Calculate initial BAC: 42 g of alcohol / 43220.8 = 0.000972
- Convert to BAC percentage: 0.000972 x 100 = 0.0972
- Adjust for time: Subtract the effect of alcohol metabolism (0.015 per hour). After 1 hour: 0.0972 – 0.015 = 0.0822.
- The final BAC is approximately 0.08.