Solution

The correct answer is 400 Kbps

EXPLANATION:

A time division multiplexing system combines multiple channels by interleaving bits by time. The bit rate of the multiplexed channel is determined by the number of time slots and the bit rate of the individual channels.

To find the bit rate when multiplexing four 100 Kbps channels using a time slot of 2 bits, we can follow these steps:

1. Determine the total number of channels: There are 4 channels, each operating at 100 Kbps.

2. Calculate the total bit rate of the channels:
        \( \text{Total Bit Rate} = \text{Number of Channels} \times \text{Bit Rate per Channel} = 4 \times 100 \text{ Kbps} = 400 \text{ Kbps}\)

3. Consider the time slot size: The time slot of 2 bits means that each channel is transmitting 2 bits in each time slot. However, since we are combining the channels, the total bit rate does not change based on the size of the time slot for each channel. 

Conclusion:

• The overall bit rate after multiplexing is: 3) 400 Kbps.

Mistake PointsThe official question was some typing mistake "A multiplexes combines for "There should be four not "for" " 100 Kbps channels using a time slot of 2 bits. What is the bit rate ?"