Help on signal question

[shermaine]

I have a few question from pas yrs exam which i hope to check with you guys what's the correct answer. Can kindly advise me?

Q(1) signal Xa(t) = pi sin(5t + 6). By skecthing Xa(t) & Xa(t)^sq
(a) Average of Xa(t) =0
(b) Average power Xa(t) = 0
(c) rms value of Xa(t) is equal to sq 0.5 pi
(d) All the above

Q(2) Xa(t) = e^5e^j(6t + 7). By sketching Xa(t) and Xa(t)^2
(a) Signal has amplitude of e^5e^j7
(b) phase signal is given by factor e^j7
(c) both correct
(d) both wrong

Q(3) Does cos(2t) + e^jt & cos(2t) + e^t have fourier series?
(a) no for both
(b) yes for both
(c) yes & no
(d) none of the above

Q(4) Telephone speech has no bradd. Any signal from 0.3 to 3.4khz is transmitted. To restore the brass of the signal, so it will have better hi-fi.
(a) Square the signal so as to create dc or low fre
(b) pass the signal into equalizer to enhace low freq spectrum
(c) convolue the signal sinusoid having frd 0 to 3khz
(d)impossible to be done

Q(5) y(t) of a robot is input using x(t) applied to a motor according to dy(t)/dt + 3y(t) = 2x(t)
(a) system is a second orde
(b) freq response is the (a1 + a2jw)/(a3 +a4jw)
(c) impulse response of sinuoid
(d) none of the above

Q(6) Audio equalizer is used to compensate for variation in freq.CD band is divided into 5 band equalizer
Freq(hz) 100 300 1000 3000 10000
Gain(db) 0 0 0 0 0
(a) Output very small as gain are set to zero
(b) output same as input
(c) both are correct
(d) both are wrong


Here's my answer:

(b)
(b)
(a)
(b)
(a)
(a)

can someone advise me which part of my answers are wrong?
Please kindly advise.Thanks.