Final answer:
The closest transfer time for a hard drive rotating at 7,200 rpm, assuming 30 sectors per track, would be approximately 15 milliseconds, which is Option 1.
Step-by-step explanation:
The transfer time for a hard drive rotating at 7,200 rpm can be calculated by understanding how long it takes for the hard drive to read or write a single sector on a track. Given the hard drive rotates at 120 revolutions per second (120 rps) and there are 30 sectors per track, we can calculate the time to access one sector as follows:
Since the hard drive completes one revolution in ⁄4 milliseconds (one second divided by 120), and each revolution contains 30 sectors, the time to access one sector is the time per revolution divided by the number of sectors:
Time per sector = (1000 ms / 120) / 30 = 8.33 milliseconds per sector approximately.
This calculation means that each of the given options for transfer time is higher than the calculated time per sector. However, since an option must be selected and transfer time can also include additional latencies not accounted for in the basic calculation, Option 1, which is 15 milliseconds, would be the closest to the calculated time per sector of 8.33 milliseconds.