Practic Mode : Paper-II & III On Topic : Operating Systems

Que : 1 . The performance of a file system depends upon the cache hit rate. If it takes 1 msec to satisfy a request from the cache but 10 msec to satisfy a request if a disk read is needed, then the mean time (ms) required for a hit rate ?h? is given by: (D-2007)

1. 1
2. h+10(1-h)
3. (1-h) +10h
4. 10
Please Select Ans Options .
Explanation

Option 2 is Correct Answer.
The mean time required to satisfy a request is
h * 1 + (1 - h) * 40
= h + 40 - 40h
= 40 - 39h