As a certain sound wave travels through the air, it produces pressure variations (above and below atmospheric pressure) given by ?P = 1.31 sin(?x - 332?t) in SI units. (Note: Use the following values as needed, unless otherwise specified. The equilibrium density of air is ? = 1.20 kg/m3. Pressure variations ?P are measured relative to atmospheric pressure, 1.013 105 Pa.) (a) Find the amplitude of the pressure variations. (b) Find the frequency of the sound wave. (c) Find the wavelength in air of the sound wave. (d) Find the speed of the sound wave.