A uniform tube of length 60.5 ~cm is held vertically with its lower end dipped in water. A sound source of frequency 500 ~Hz sends sound waves into the tube. When the length of tube above water is 16 ~cm and again when it is 50 ~cm , the tube resonates with the source of sound. Two lowest frequencies (in Hz ), to which tube will resonate when it is taken out of water, are (approximately).