Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 5

A transmission system sends out information at 200,000 b/s. During the transmission process, fluctuation noise is added to the signal so that at the decoder output the signal pulses are 1 V in amplitude and the rms noise voltage is 0.2 V.
( a ) Assuming that ones and zeros are equally likely to be transmitted, what is the average time in which an error occurs
( b ) How is this time changed if the voltage amplitude is doubled with the rms noise voltage remaining the same