Four processes A, B, C and D are ready to execute, having arrived in that order. They require different numbers of quanta to complete and request different priorities (1 is lowest, 4 is highest):

Process A requires 2 quanta, requested priority 1

Process B requires 5 quanta, requested priority 3

Process C requires 3 quanta, requested priority 2

Process D requires 4 quanta, requested priority 4.

What is the pattern of execution under the following scheduling strategies:

i. first in, first out

ii. round-robin

iii. priority.

Give your answer by showing which process executes at each quantum until all processes complete, for example: A C C B B

What is the total number of quanta required in each case?