A student stands several meters in front of a smooth reflecting wasll, holding a board on which a wire is fixed at each end. The wire, vibrting in its third harmonic is 75.0 cm long, has a mass of 2.25 g, and is under a tension of 400 N. A second student, moving towards the wall, hears 8.30 beats per second. What is the speed of the student apporaching the wall? Use 340 m/s as the speed of sound in air.