Please help me with this Physics Problem

The diagram shows the direction of a sound wave travelling in a metal sheet.

The frequency of the sound wave in the metal is 250 Hz.

a. Particle P in the metal sheet performs simple harmonic oscillations. When the displacement of P is 3.2 μm the magnitude of its acceleration is 7.9 m s-2. Calculate the magnitude of the acceleration of P when its displacement is 2.3 μm. [2 MARKS]

b. The wave is incident at point Q on the metal–air boundary. The wave makes an angle of 54° with the normal at Q. The speed of sound in the metal is 6010 m s–1 and the speed of sound in air is 340 m s–1. Calculate the angle between the normal at Q and the direction of the wave in air. [2MARKS]

c. State the frequency of the wave in air. [1 MARK]

d. Determine the wavelength of the wave in air. [1 MARK]

e. The sound wave in air in (c) enters a pipe that is open at both ends. The diagram shows the displacement, at a particular time T, of the standing wave that is set up in the pipe.

On the diagram, at time T, label with the letter C a point in the pipe that is at the centre of a compression. [1 MARK]