Digital systems are sensitive to electronic noise. in digital communication, we sometimes represent noise as an increase in the variance of the digital signal. when the variance of the digital signal is greater than a set level, the digital communication channel is considered unusable. a telecommunication engineer is required to assess the usefulness of a channel. if the channel true standard deviation is greater than 0.2 volts then the channel is not acceptable for use. the engineer evaluates the channel using 10 trials and obtains a standard deviation (for the 10 trials) of 0.10954 volts. the engineer then evaluates the channel using 101 trials and obtains a standard deviation (for the 101 trials) of 0.16740 volts. (total: 8 marks) a) in the case of the 10 trials, determine the confidence level for the channel standard deviation if the upper bound (i. e. maximum value) of the confidence interval is the largest standard deviation that will allow the channel to be used (i. e. 0.2 volts). (2 marks) b) in the case of the 101 trials, determine the confidence level for the channel standard deviation if the upper bound of the confidence interval is the largest standard deviation that will allow the channel to be used (i. e. 0.2 volts). (2 marks) c) based on the confidence interval, what is the expected number of times that the channel will be not acceptable for the 10 trials if this was repeated 200 times? (2 marks) d) based on the confidence interval, what is the expected number of times that the channel will be not acceptable for the 101 trials if this was repeated 200 times?