Technician A states that a reading of 250 mv from the O2 indicates a rich exhaust. Technician B states that when the PCM receives this 250mv reading it sends out a rich command to the injectors. Who is correct?

Technician B is correct

Explanation:

An oxygen sensor will generate about 1.0 volts when the fuel mixture is rich and there is little unburned oxygen in the exhaust. When the mixture is lean, the sensor's output voltage will drop down to about 0.1 volts.

An o2 sensor cannot accurately measure how rich or how well an exhaust system is.

Therefore, Technician B is correct.

the independent variable, or the one that is intentionally manipulated is the speed.

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up