To define the quantity and scale for the x-axis of a piecewise linear graph of the fee structure based on the dog's weight, we need to consider the weight ranges provided:
- Dogs under 15 lbs are charged a flat rate of $30.
- Dogs between 15 lbs and 50 lbs are charged a flat rate of $35.
- Dogs over 50 lbs incur additional costs based on how much they weigh over 50 lbs.
Given that the weight categories are defined in increments of 5 lbs, and that we need a range that comfortably includes all the weight categories (from 0 lbs up), the best choice for the scale on the x-axis would be increments of weight suitable to represent the various fee structure changes.
Considering the standard increments:
- The ranges are clearly defined at break points of 15 lbs and 50 lbs.
- Additionally, the increments of additional charges over 50 lbs occur every additional 5 lbs.
Thus, the best scale to represent the data would be in increments of 1 lb, allowing for precise tracking of weight changes up to at least the point where significant charge changes occur.
Therefore, the option that best defines the quantity and scale for the x-axis is:
weight; 1