Waves from a radio station have a wavelength of 319 m. They travel by two paths to a home receiver 19.2 km from the transmitters. One path is a direct path, and the second is by re?ection from a mountain directly behind the home receiver. What is the minimum distance from the mountain to the receiver that produces destructive interference at the receiver? (Assume that no phase change occurs on re?ection from the mountain.) Answer in units of m