In standard microeconomic theory, the short run is defined as a production period in which at least one input is fixed while other inputs can be varied.

### Why this is right Both statements are explicitly listed as assumptions of production functions in the note. They allow analysis of changes in output as variable inputs change while some inputs remain fixed. ### The concept A fixed input does not change over the period being considered, while a variable input can be adjusted. Fine divisibility assumes quantities can be varied in small increments rather than only in large indivisible blocks. These are analytical assumptions and may not perfectly describe every real production setting. ### Remember Production analysis often distinguishes fixed inputs from variable inputs.