Calling all mathmeticians.

[Chris_H 0]

I need help on the question, #8 "B" and "C"

The line of best fit is y=-.0094x+o.943 and the point on the line is x=2.530851 and y=0.7762. The back of the book says answer for "B" is .835, but I need to know how to do it, and the idiodic teacher will not help, so I am forced to seek elsewhere. You guys helped last time and am confident you will prevail again. Thanks.

As yuo can see I lack in english intelligence as well.

[Kobe 0]

That doesn't make any sense. Just by looking at the slope of the graph, it is not possible that his blood alcohol level went from .835 to .06 in 2.5 hours.

EDIT: Ok that changes everything. I got it. The problem that you're facing is that you're trying to find that point on the line in A when you're suppose to find that point on a line that's PARALLEL to that line in A. The only thing that you can get off of that line of best fit is the slope to use as info. Drop in the x coord (2.5 hours) and the Y (the 0.06) and find the y-intercept. The y-intercept is where time = 0 (or x equals 0 in other words) and that's where his blood alcohol level (the y-coord) is when he began driving. Ask questions if you don't get it.

[Chris_H 0]

My bad, it`s .0835

[Kobe 0]

Oh I forgot to answer C. You're assuming that his blood alcohol level decreases with time the same way that the researchers have found (hence the use of the slope in part A to use in part B ).

[rh_joel 0]

Since the equation of best fit is y=-0.094x + 0.943 that tells you that every hour the amount of alcohol per 100 litres decreases by 0.094. (that's what the slope means... change in alcohol per hour..remember slope is the number in front of the x) (Remember that this equation is just an equation about how the amount of alcohol in the blood decreases over time...it has nothing to do with the person stopped by the police)

Since the person told the police that he had been driving for 2.5 hours that means that his blood levels 2.5 hours ago must have been (2.5)(0.094)=0.025 plus what is it now (the police tested it to be 0.06 now).

That gives you 0.025 + 0.06 which gives you 0.0835

Any more questions? :P

[Buzz_LightBeer 974]

Any more questions? :P

Just one, what type of math are you doing that 0.025 + 0.06 = 0.0835? ;)

[JR Boucicaut 3804]

He's drunk, that's why! :)

[Guest Stax7]

Holy S**t listening to this it sounds like genius talk.

[Timber 0]

Go back to you're good old y=mx + b equation where m=the slope and b=the y intercept. You already know that the slope of the alcohol metabolism formula is -.0094 (or you could calculate it by averaging the 3 xy data points: slope= change in y divided by change in x). If you enter 0.06 for the y intercept(concentration=.06 at time=0) and -2.5 for x (2.5 hours ago), you get .0835 for y. You assumption is that this individuals alcohol metabolism curve (at least the slope over the alcohol concentration range given) matches the researchers data.