A continuous-time signal is sampled

A continuous-time sigA continuous-time signal is sampled and then transmitted as a PCM signal. The random variable at the input of the decision device in the receiver has a variance of 0.01 volts2
(a) Assuming the use of polar NRZ signaling, determine the pulse amplitude that must be transmitted for the average error rate not to exceed 1 bit in 108 bits.
(b) If the added presence of interference causes the error rate to increase to 1 bit in 106 bits, what is the variance of the interference?nal is sampled