In a certain RDT protocol, we do not proceed to sending the next packet over the channel, until we are notified by the receiver that the previous packet has arrived safe and sound at the receiver. The physical layer protocol enables sending R-64 M bits/s over the channel. The channel utilisation is measured to be 40% using a packet of size P. If the channel is characterised by an RTT of 3 ms, calculate the packet size used in the measurement.

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