Final answer:
The critical ratio is calculated as the time remaining for a resource divided by the annual production rate, known as the R/P ratio.
Step-by-step explanation:
The critical ratio is calculated as the time remaining divided by the production rate.
In the context of resource management, the R/P ratio, which stands for reserves-to-production ratio, is used to assess the time remaining for a resource. To compute this ratio, the total remaining resource (R) is divided by the annual production (or consumption) rate (P). The result of this division is the estimate of the time available for the resource at the present rate, assuming no discoveries of additional resources or changes in the rate of use.
For example, if a resource has 1,000 units left (R) and the current production rate is 100 units per year (P), the R/P ratio would be 1,000 divided by 100, which equals 10 years. This implies that at the current production rate, the resource will be available for 10 more years.