Most blood alcohol concentration (BAC) calculations are based on the Widmark formula

=/

where BAC is the blood alcohol concentration, measured in % (grams) per volume; e.g., =0.14 means 14% of a gram, i.e., 0.14 grams of alcohol per 100 millilitres of blood.

A is the adjusted mass of alcohol consumed, computed from

=0.1(amount of alcohol consumed, in grams)A=0.1(amount of alcohol consumed, in grams)

(keep in mind that one drink = 14 g of alcohol);

r is the Widmark factor, which accounts for sex differences in alcohol absorption: Here we take =0.66r=0.66 for female adults, and =0.73r=0.73 for male adults;

W is the body mass in kilograms;

t is elapsed time (in hours) since the start of drinking. (Thus, =0t=0 marks the start of drinking.)

The symbol is the alcohol elimination rate, in litres per hour. An average elimination rate (if alcohol is taken on empty stomach) is =0.015=0.015 L/hr.

John needs to drive home, and decides to wait until his BAC falls just below 0.05 (the BAC of 0.05 or higher can result in a charged for impaired driving; the BAC of 0.08 or higher is classified as driving under influence; both offences carry severe consequences and possible criminal charges).

The code below creates a table of values for BAC and plots it over the interval [0,12],[0,12], where =0t=0 represents 8pm, the time when John started drinking. (Notice that this model stops making biological sense after about =8t=8)

Keep in mind that t and BAC are lists, and that you can print their individual values, such as [23]t[23] or BAC[51]

Examine the table of values for BAC to find the time when John's BAC falls below 0.05 for the first time. Fill in the blank: John's BAC falls below 0.05 for the first time 5 hours and ___ minutes (round off to the nearest integer minute) after 8pm.