SOLUTION: This problem is not from my textbook it is a worksheet problem. A(x)= -0.015x3+1.05x gives the alcohol level in an average person’s blood x hrs after drinking 8 oz of 100-proof wh

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: This problem is not from my textbook it is a worksheet problem. A(x)= -0.015x3+1.05x gives the alcohol level in an average person’s blood x hrs after drinking 8 oz of 100-proof wh      Log On


   

Question 127496: This problem is not from my textbook it is a worksheet problem.
A(x)= -0.015x3+1.05x gives the alcohol level in an average person’s blood x hrs after drinking 8 oz of 100-proof whiskey. If the level exceeds 1.5 units, a person is legally drunk. Would a person be drunk after 3 hours?
The answer choices are
Yes
No
Found 2 solutions by checkley71, bucky:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
A(X)=-.015X^3+1.O5X
A(3)=-.0153X^3+1.05*3
A(3)=-.0000003582+3.15
A(3)=3.149999642 YES.

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
.
A%28x%29=+-0.015x%5E3%2B1.05x
.
where x is the amount of time after a person drinks 8 oz of 100-proof whiskey and A(x) represents
the number of units of alcohol in the blood of an average person.
.
To find the number of units of alcohol in the blood after 3 hours have passed, just substitute
3 for x and the equation becomes:
.
A%283%29=+-0.015%2A%283%29%5E3%2B1.05%2A%283%29
.
When you cube the 3 you get 3*3*3 = 27. Substituting 27 for 3 cubed changes the equation to:
.
A%283%29=+%28-0.015%2A27%29%2B1.05%2A3
.
Do the multiplication in the two terms and the equation becomes:
.
A%283%29+=+-0.405+%2B+3.15
.
A%283%29+=+2.745
.
This tells you that after 3 hours there are still 2.745 units in the blood of an average person.
Since this is more that the 1.5 units that is the dividing line between being legally sober
and legally drunk, this individual is still inebriated. Take his keys and call a taxi to
take him home.
.