Question on external memory(computer architecture)


consider a single-platter disk with the following parameters:
rotation speed:7200 rpm
number of tracks on one side of platter:30000
number of sectors per track:600
seek time:one ms for every hundred tracks traversed.
let the disk receive a request to access a random sector on a random track and assume the disk head starts at 0.then find the 1)average rotational latency?
2)transfer time for a sector?


1.rotation speed:7200 rpm=120 rev per second.
average rotational latency=1/2r=4.167ms

2.transfer time for a sector

transfer time for a complete track =1/r=8.33msec
transfer time for a sector=8.33m/600=13.89usec