Step 1 :The 1-hour growth (or decay) factor for the number of mg of caffeine in Trey's bloodstream can be calculated by dividing the amount of caffeine in his bloodstream after 1 hour by the initial amount of caffeine in his bloodstream.
Step 2 :Let's denote the initial amount of caffeine as \(initial\_caffeine\) and the amount of caffeine after 1 hour as \(caffeine\_after\_1\_hour\).
Step 3 :From the table, we know that \(initial\_caffeine = 300\) and \(caffeine\_after\_1\_hour = 270\).
Step 4 :Then, the 1-hour growth (or decay) factor, denoted as \(growth\_factor\), can be calculated as \(growth\_factor = \frac{caffeine\_after\_1\_hour}{initial\_caffeine} = \frac{270}{300} = 0.9\).
Step 5 :Final Answer: The 1-hour growth (or decay) factor for the number of mg of caffeine in Trey's bloodstream is \(\boxed{0.9}\).