Which statement is correct? a. Two states are equivalent if the sates have the same output, and the samenext state for the same input vaues.
b. When removing an equivalent state, the incoming and outgoing transitions can be removed.
c. Given two equivalent states, either state can be removed.
d. Removing a state may reduce the size of a controller's state register and/or logic.

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.