30. We need to send 1000 frames. We ignore the overhead due to the header and trailer. Data frame Transmission time = 1000 bits / 1,000,000 bits = 1 ms Data frame trip time = 5000 km / 200,000 km = 25 ms ACK transmission time = 0 (It is usually negligible) ACK trip time = 5000 km / 200,000 km = 25 ms Delay for 1 frame = 1 + 25 + 25 = 51 ms. Total delay = 1000 × 51 = 51 s