#### Answer

$0.035$

#### Work Step by Step

We will use the following formula for the blood alcohol concentration (BAC) of a person who has been drinking.
BAC = (number of oz)(% alcohol)(0.075) / (body weight in lb) - (hr of drinking)(0.015).
We are to determine the BAC for a 135 lb woman who has ingested three 12-oz-beers (36 oz) each having 4% alcohol, in 2 hours. Estimate to the nearest thousandth.
Number of oz = 36
% alcohol = 4
body weight = 135
hr of drinking = 3
We will use the formula:
$BAC=(36)(4)(0.075)\div(135)-(3)(0.015)$
$=10.8\div135-3(0.015)$
$=0.008-0.045$
Therefore, the BAC of the person is:
$BAC=0.008-0.045=0.035$