Hard drive with a maximum transfer rate of 1 Mbytes per second so that means
1MB transfer in 1 sec
1 B transfer in 1/106 sec
2KB transfer in (2*103 / 106 ) * 106 microsec= 0.002 * 106 microsec = 2000 microsec, this is our transfer time ...(i)
Now, total number of cycles are ( 300 + 500) = 800
CPU operating at a clock frequency of 100 megahertz , now 100 MHz = 100 * 106 Hz = (1/108) * 106 microsec = 1/100 microsec
so , total cycle time is 800* (1/100) microsec = 8 microsec ....(ii)
so , the percentage of CPU TIME consumed in Handling the hard drive is( assuming here burst mode is used)
= 8/(8+2000) * 100
= (8/2008) * 100
= 0.003984 * 100
= 0.3984%