6.4. Verify (6.5). 6.5. Consider an MA(1) process xt = wt + qwt1, where q is a parameter. (a) Derive a formula for the power spectrum of xt, expressed in terms of q and w. (b) Use arma. spec() to plot the spectral density of xt for q > 0 and for q < 0 (just select arbitrary values). (c) How should we interpret the spectra exhibited in part (b)?

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function. a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.