a modem transmits a+2 voltage signal into a channel. the channel adds to this signal a noise term N that drawn from the set 0.-1, -2, -3 with respective probabilities A 4/10, 3/10, 2/10,1/10 . Let Y denote the Signal received which is the original signal plus noise. Find the following:

The pmf of the Noise N

The pmf Of the received signal values Y

The average E[Y]

The variance var[Y]