The bit-duration for each signal is the reciprocal of the sampling rate multiplied by the number of bits per sample.
Given:
- Sampling rate = 12 kHz = \( 12 \times 10^3 \) samples per second,
- Bits per sample = 8 bits,
- Number of signals = 24.
The bit rate per signal is:
\[
\text{Bit rate} = 12 \times 10^3 \times 8 = 96000 \, \text{bits per second}.
\]
The bit-duration is the reciprocal of the bit rate:
\[
\text{Bit-duration} = \frac{1}{96000} \, \text{seconds}.
\]
Converting to microseconds:
\[
\text{Bit-duration} = \frac{1}{96000} \times 10^6 \, \mu s = 10.42 \, \mu s.
\]
Thus, the bit-duration is approximately \( 0.44 \, \mu s \).