Algebra-2

Question Analysis
This problem assesses the ability to calculate the hourly decay rate of an exponentially decaying quantity.

Key Concept Explanation
Exponential decay can be modeled by the formula , where is the quantity after time , is the initial quantity, and is the decay rate (negative for decay).

Step-by-step Solution
1. Identify the given values: Initial quantity , final quantity , and time hours.
2. Substitute the values into the exponential decay model: