Suppose an operating system executes 100 processes in a second, and the time required for a context switch is negligible. Note that one millisecond is 1/1000 seconds. a. (4%) If each of those processes uses one time slice, how long is a time slice in terms of millisecond? b. (4%) If each of 1/4 of those processes uses two time slices and each of the other processes uses only one time slice, how long is a time slice in terms of millisecond?