38. IE • On a day with a temperature of 20 °C and no wind blowing, the frequency heard by a moving person from a 500-Hz stationary siren is 520 Hz.

(a) The person is (1) moving toward, (2) moving away from, or

(3) stationary relative to the siren. Explain.

(b) What is the person’s speed? Assume any movement is along the line joining the siren and the person.