In persistent CSMA, we sense the medium if medium is busy we wait if its free we send with a probability p in that slot or differ to next slot with probability 1-p, but here in first line it says that it transmits immediately and then do as stated

In P-persistent CSMA network there are 5 systems in a slot. The probability of station not transmitting the data is 0.6. Only two stations should transmit the data to avoid collision. What is the probability that channel is collision free? My answer is 0.6825 and answer given is 0.34 - 0.35. I solved this as P (no collision) = either 2 stations are transmitting or 1 station or none.

If CSMA transmits 8 stations network data in single channel whats is the chip code for station 5 {Assume that W1=[+1]} how to solve it solution given is. 1111-1-1-1-1.

Consider CSMA/CD LAN with bandwidth 10 Mbps and propagation delay of 5 μsec. Repeaters are not allowed in this system. Data frames are 512 bits long, including 32 bits of header, checksum and other overhead. The first bit slot after a successful transmission is ... frame. The effective data rate of the network is ________ (in Mbps). (Excluding overhead, assuming that there are no collisions)

In standard ethernet with transmission rate of 20 Mbps, the length of the cables is 2500 m and the size of frame is 512 bits. The propagation speed of a signal in a cable is 2 × 108 m/s. The percentage of the time channel is idle or not used by a station is _________ (in approximate integer value).