3) An adult human at rest inhales and exhales approximately 520 ml of air (called the tidal volume) in approximately 5 sec. However, at the end of each exhalation, the lungs still contain a volume of air, called the functional residual capacity (FRC), which is approximately 2300 ml. (a) What volume of air is in the lungs after inhalation? (b) What volume of air is in the lungs after exhalation? (c) What is the period of a complete respiratory cycle?