If two fair coins are flipped and at least one of the outcomes is known to be a head, what is the probability that both outcomes are heads?

An application loads $$100$$ libraries at startup. Loading each library requires exactly one disk access. The seek time of the disk to random location is given as $$10$$ $$ms$$. Rotational speed of disk is $$6000$$ $$rpm.$$ If all $$100$$ libraries are loaded from random locations on the disk, how long does it take to load all libraries? (The time to transfer data from the disk block once the head has been positioned at the start of the block may be neglected).

Consider the following table of arrival time and burst time for three processes $$P0,P1$$ and $$P2$$.

Process	Arrival Time	Burst Time
P0	0 ms	9 ms
P1	1 ms	4 ms
P2	2 ms	9 ms

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only a arrival or completion of processes. What is the average waiting time for the three processes?

Let the time taken to switch between user and kernel modes of execution be $${t_1}$$ while the time taken to switch between two processes be $${t_2}$$.

Which of the following is TRUE?