Question

A doctor prescribes a 300-mg antibiotic tablet to be taken every eight hours. Just before each tablet is taken, 20% of the drug remains in the body. (a) How much of the drug is in the body just after the second tablet is taken? After the third tablet?

Answer 1

Answer:

So after the second  tablet there is 360-mg of drug in the body.

So after the third  tablet there is 372-mg of drug in the body.

Step-by-step explanation:

We know that a  doctor prescribes a 300-mg antibiotic tablet to be taken every eight hours. Just before each tablet is taken, 20% of the drug remains in the body.

We know that  20%=0.2.

We conclude that after the first pill, 300mg of the  drug is in the body.

We have the following formula, to calculate how much mg of the drug is in the body after the second tablet:

$300+20\%\cdot 300=300+0.2\cdot 300=300+60=360$

So after the second  tablet there is 360-mg of drug in the body.

We have the following formula, to calculate how much mg of the drug is in the body after the third tablet:

$300+20\%\cdot 360=300+0.2\cdot 360=300+72=372$

So after the third  tablet there is 372-mg of drug in the body.