I was not convinced by the solution provided so, I made my own analysis.
Given propagation delay is 225-bit times, and since bandwidth is $10^7 bps$, so my $T_p=22.5 \mu s$
Suppose at t=0, both A and B start to transmit.
At t=$22.5 \mu s$, both A and B will detect a collision.
Now time taken to transmit 50-bit jam signal=$\frac{50}{10^7}=5 \mu s$
At t=$27.5 \mu s$ both A and B would have transmitted their jam signals.
These signal bits would take another $T_p=22.5 \mu s$ to reach nodes A and B. A would get B's jam signal and B would get A's jam signal, assuming A and B are two farthest nodes on this network.
So, at t=$27.5+22.5=50 \mu s$, my jam signal would have been received by both A and B.
Now, my question is whether at t=$51 \mu s$ my channel would look idle to A and B or at $50 \mu s$ ?
