Final answer:
To estimate the average shelf life of a brush, one must divide the time period by the number of items sold. This question lacks enough information for a precise calculation and involves assumptions that may not hold true in a real-world scenario.
Step-by-step explanation:
The question of calculating the shelf life of an item like a Furminator brush with the given inventory data isn't strictly a standard mathematical problem, as it doesn't provide enough direct information regarding how frequently the brushes are sold or used. To calculate shelf life, you typically need to know the rate at which an item sells or the period it takes for the inventory to be depleted. However, we can attempt to deduce an average shelf life from the information given, assuming a consistent rate of sales or usage over time.
If we start with an inventory of 2, buy 8 more during the year, and end with 3, we have sold 7 brushes (because 2 + 8 - 3 = 7). If we assume these 7 brushes were sold evenly over the course of a year, we could divide the total time period (1 year) by the number of brushes sold to get an approximate average shelf life per brush. However, this method relies on many assumptions and is not precise.