You must understand fixed overhead expenses in order to understand absorption costing and variable costing. Fixed overhead consists of expenses that do not change with your level of production. Examples of fixed overhead include rent, insurance, wages for permanent full-time employees, and lease payments on equipment.
Whereas it may be safe to start a horse as early as two years of age, you must reasonably moderate the demands you are about to place on the developing horse. One hour of riding work may be just fine for a fully developed horse, but it is most often unacceptable for a two-year old.
7, in general, is an age where those things come together, some children will be ready at 6, others not until 8 or even 10. In addition, before you start formal lessons, you want to know that they can graduate to independent control over the horse within 3 - 6 months. If you keep a child on a lunge line or lead line for too long, it's much harder for them to become independent riders later.