A plumber is trying to fix a clog in a vertical pipe, but does not know how far down in the pipe the clog and the water level is. He is a good whistler, so he whistles into the open end of the pipe and finds that a frequency of 104hz (cycles per second) returns a loud resonant sound. He knows the speed of sound is 340 m/s. Calculate the depth of the air in the pipe above the clog.