Final answer:
To find the amount of Tylenol left in the bloodstream after 15 hours, we substitute x = 15 into the given equation y = 500(0.75)^x and evaluate it.
Step-by-step explanation:
The amount of Tylenol in the bloodstream can be modeled by the equation y = 500(.75)^x, where y represents the amount of Tylenol and x represents the time in hours. To find the amount of Tylenol left in the bloodstream after 15 hours, we substitute x = 15 into the equation:
y = 500(.75)^15
Using a calculator, we can evaluate this expression to be approximately 2.10. Therefore, the amount of Tylenol left in the bloodstream after 15 hours is approximately 2.1 (rounded to the nearest tenth).