Math Central - mathcentral.uregina.ca Math Beyond School return to top Math in the Squad Car RCMP officers also use math while on patrol.  The legal drinking limit for an adult that is still able to drive is a blood alcohol content (BAC) of .08.  That is, any measurement higher than that makes driving illegal, and drivers can be charged or fined.  The measurement of .08 means .08 grams of alcohol per 100mL of blood.  The mouth absorbs alcohol, so the alcohol on the driver’s breath is related to the amount of alcohol in their blood.  The ratio of breath alcohol to blood alcohol is 2100 to 1 (this ratio can vary slightly depending on the individual).  This means that the alcohol content of 2100 milliliters of exhaled air is the same as the amount of alcohol in 1 milliliter of blood.  Alcohol is then expressed as a percentage amount in the blood, where the legal limit is .08%.   RCMP officers use a breath test called a Breathalyzer to determine the BAC of a driver they suspect may have been drinking.  And although the Breathalyzer does most of the math, it is important to understand how it works and the math behind it.  RCMP officers also use math when writing tickets.  Let’s look at speeding tickets as an example.  In the province of Saskatchewan, speeding tickets can be expressed as linear equations.  That is, the faster a person drives (in excess of the posted speed limit), the more their ticket will be if they get caught.  If the vehicle is traveling 0 – 30 km/h over the posted limit, the fine is \$70 plus \$1 for every km/h over the limit.  There is also a Victim Surcharge of \$30 if the total cost of the ticket is less than \$100.  So, let’s say the posted limit is 110 km/h and a vehicle is traveling 125 km/h.  If the driver were to get caught, finding the cost of the ticket would require some mathematical calculations.  First of all, 125 km/h is 15km/h over the limit.  The base ticket rate is \$70, plus \$1 for each km/h over (\$15).  This brings the total amount of the ticket to \$85.  Since this is less than \$100, the Victim Surcharge would be applied, summing up the total fine to \$115.  RCMP officers need to do this math quickly, while the driver waits patiently in their car.  They also need to be very accurate.  The above rate is not the only rate officers need to know.  If a vehicle is traveling 31 – 50 km/h over the limit, the fine is \$70 plus \$2 for every km/h over the posted limit.  There is also a \$40 Victim Surcharge, regardless of the total amount of the ticket.  If a vehicle is traveling 51+ km/h over the speed limit, then the fine is \$140 plus \$4 for every km/h over the limit.  There is also a Victim Surcharge of \$40 (if the ticket is less than \$200) or \$50 (if the ticket is more than \$200).
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