a weather balloon carries instruments that measure temperature,pressure and humidity as it rises through the atmosphere.Suppose such a balloon has a volume of 1.2 m^3 at sea level where the pressure is 1 atm and the temperature is 20 degree Celsius.When the balloon is at an altitude of 11 km(36,000ft) the pressure is down to 0.5 atm and the temperature is about -55 degree Celsius,what is the volume of the balloon then.