Juanita is lying in a hammock in her garden and listening to music on her portable radio tuned to WMCB (1408 kHz), a station located 98 km from her home. A plane, about to land at the airport, flies directly overhead and causes destructive interference. Juanita estimates the plane to be at least 500 m over her head. Assume there is a 180 ° phase shift when the radio wave reflects from the airplane.
(a) What is the closest possible distance between Juanita and the plane if her estimation is correct?
(b) Find two other possible elevations, the next one lower and the next one higher, for the plane in case her estimation is off.