A machine's efficiency $$ E $$ (in units per hour) and the t...

Question Analysis
This problem assesses the understanding of the constant of variation in a real-world context involving inverse variation.

Key Concept Explanation
In an inverse variation, the product of the two variables is a constant, denoted as . Mathematically, if and are inversely proportional, then .

Step-by-step Solution
1. Substitute the given values into the equation :