A warehouse on a dock has two open doors. A boat sounds its horn from across the river. Two people are D = 150m away from the wall nearest the boat and s = 20m from each other. To person A, directly between the doors, the sound is loud and clear. To person B, the sound is barely audible. The sound waves have a wavelength of 3.0m. If person B is at the first intensity minimum, what is the distance d between the doors?

A warehouse on a dock has two open doors. A boat sounds its horn from across the river. Two people are D = 150m away from the wall nearest the boat and s = 20m from each other. To person A, directly between the doors, the sound is loud and clear. To person B, the sound is barely audible. The sound waves have a wavelength of 3.0m. If person B is at the first intensity minimum, what is the distance d between the doors?