Question 1196944:  The remaining concentration of a drug in a person’s bloodstream is modeled by the relation C=C0(1/2)^t/8, where C is the remaining concentration of the drug in the bloodstream in milligrams per milliliter of blood, C0 is the initial concentration, and t is the time, in hours, that the drug is in the bloodstream.
 
What is the half-life of this drug?
 
A nurse gave a patient this drug, which was 20 mg/ml. What is the concentration of this drug in 3.5 hours? 
 Found 2 solutions by  math_tutor2020, josgarithmetic: Answer by math_tutor2020(3817)      (Show Source): 
You can  put this solution on YOUR website!  
Part A) What is the half-life of this drug?
 
 
There are a few ways to write a half-life formula 
One such way is to write it like this 
y = a*(1/2)^(t/H)
 
 
the variables are 
a = initial amount 
H = half-life 
t = number of time units 
y = amount remaining after t time units elapsed
 
 
We see that H = 8 is the half life. 
Every 8 hours, the drug concentration in the bloodstream will cut in half.
 
 
Answer: 8 hours
 
 
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Part B) A nurse gave a patient this drug, which was 20 mg/ml.  
What is the concentration of this drug in 3.5 hours?
 
 
 
We have a = 20 mg per mL as the initial concentration. 
In other words, for each mL of blood, the patient gets 20 mg of the drug.
 
 
This will replace the C0 in the equation C=C0(1/2)^(t/8) since C0 takes the role of 'a' which is the initial value.
 
 
So we have C=20(1/2)^(t/8)
 
 
Now let's determine C when t = 3.5 hours
 
 
C=20(1/2)^(t/8) 
C=20(1/2)^(3.5/8) 
C=14.768261459395 
C=14.768 
Round this value however needed, or however your teacher instructs.
 
 
Answer: Approximately 14.768 mg/mL 
 
 Answer by josgarithmetic(39630)      (Show Source): 
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