Frames of 1000 bits are sent over a 1-Mbps channel using a geostationary satellite whose propagation time from the earth is 270 msec Acknowledgements are always piggybacked onto data frames The head?

Let t=0 denote the start of transmission.At t=1 msec,the first frame has been fully
transmitted.At t=271 msec,the first frame has fully arrived.At t=272 msec,the frame
acknowledging the first one has been fully sent.At t=542 msec,the acknowledgement-bearing
frame has fully arrived.Thus, the cycle is 542 msec.A total of k frames are sent in 542 msec,for an
efficiency of k/542.Hence
(a)k=1,efficiency=1/542=0.18%
(b)k=7,efficiency=7/542=1.29%
(c)k=4,efficiency=4/542=0.74%