Final answer:
To find out how much of the drug is in the body just after the second tablet is taken, you need to calculate the amount of drug remaining in the body after the first tablet is eliminated and then subtract that from the initial dose of 400 mg.
Step-by-step explanation:
To find out how much of the drug is in the body just after the second tablet is taken, we need to calculate the amount of drug remaining in the body after the first tablet is eliminated and then subtract that from the initial dose of 400 mg.
- After the first tablet, 80% of the drug is eliminated, so only 20% (0.2) of the initial dose remains in the body.
- Next, we need to calculate the amount of drug remaining after the second tablet is eliminated. Since 80% of the drug is eliminated in 8 hours, we know that 20% (0.2) of the drug remains in the body every 8 hours.
- After the second tablet is taken, we multiply 0.2 by 0.2 to find the amount of drug remaining: 0.2 x 0.2 = 0.04.
- Finally, we subtract the amount of drug remaining after the second tablet from the initial dose: 400 mg - 0.04 = 399.96 mg. Therefore, just after the second tablet is taken, there is approximately 399.96 mg of the drug in the body.