One of the industrial robots designed by a leading producer of servomechanisms has four major components. components’ reliabilities are .98, .95, .94, and .90. all of the components must function in order for the robot to operate effectively. designers want to improve the reliability by adding a backup component. due to space limitations, only one backup can be added. the backup for any component will have the same reliability as the unit for which it is the backup. what will be the highest reliability the robot can achieve?

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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.