Sound waves with frequency $3000 \mathrm{~Hz}$ and speed 343 $\mathrm{m} / \mathrm{s}$ diffract through the rectangular opening of a speaker cabinet and into a large auditorium. The opening, which has a horizontal width of $30.0 \mathrm{~cm}$, faces a wall $100 \mathrm{~m}$ away (Fig. $37-28$ ). Where along that wall will a listener be at the first diffraction minimum and thus have difficulty hearing the sound? (Neglect reflections).