Final answer:
The initial value of the active ingredient in the body is 900 mg.
Step-by-step explanation:
The initial value of the active ingredient in the body can be determined by looking at the data provided. The data shows the amount of active ingredient remaining in the body over 6-hour intervals, so the initial value will be the amount of active ingredient at the start of the first 6-hour interval.
From the data, we can see that at the start of the first 6-hour interval, 900 mg of the active ingredient remains in the body. Therefore, the initial value is 900 mg.