A bicycle pump has a barrel that is 75 cm long (about 30 in.). If air is drawn into the pump at a pressure of 0.97 atm during the upstroke, how long must the downstroke be, in centimeters, to raise the pressure of the air to 5.40 atm (approximately the pressure in the tire of a 10-speed bike)? Assume no change in the temperature of the air.