When a firefighter hears the bell indicating 1/4 tank left, how much air corresponds to that warning?

The correct answer is based on the standard measurement used in firefighting regarding the air supply in a self-contained breathing apparatus (SCBA). When a firefighter hears the bell indicating that they have 1/4 tank left, it typically corresponds to approximately 25% of the total air supply.

In many SCBA configurations, the total capacity is about 140 cubic feet of air. Therefore, calculating 25% of this total gives you around 35 cubic feet of air remaining in the tank when the warning sounds. This indicator serves as a crucial safety alert, assisting firefighters in assessing their available air supply while ensuring they can retreat safely from hazardous situations.

The other options, while they may represent different volumes, do not align with the standard tank capacity measurements that are typically recognized in firefighting protocols. Thus, they do not accurately signify the 1/4 tank warning situation that firefighters are trained to recognize and respond to.