An ADSL signal uses 250 channels, each of 4 kHz bandwidth. Assume the maximum signaling rate to be 1 symbol/Hz. QAM is used within each channel with up to 64 point constellations. ADSL modem continuously monitors the quality of the channel and changes between QAM-16 and QAM-64 depending on whether the signal SNR for the channel is above or below a certain threshold T SNR . Suppose the signal SNR falls below T SNR 10% of the time. What is the average bit rate of a channel?