What do we mean by tolerance and how is it determined while designing parts? what is the relation between tolerances and the manufacturing processes used?

Two technicians are discussing the intake air temperature (iat) sensor. technician a says that the computer uses the iat sensor as a backup to the engine coolant temperature (ect) sensor. technician b says that the powertrain control module (pcm) will subtract the calculated amount of fuel if the air measures hot. who is correct

Vibration monitoring this technique uses the noise or vibration created by mechanical equipment and in seme cases by plant systems to detemine their actual condtion. a)- true b)- false

Acertain flow of air (at stp) has a velocity distribution given by v i (in ft/s). if this flow is going through a 4 ft square area in the yz-plane (centered at the origin), what is the mass flow rate (in lbm/s)?