FCFS(FIRST COME FIRST SERVED) question

Question 1

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	4
P2	2	3
P3	4	2

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	4	4	4	0
P2	2	3	7	5	2
P3	4	2	9	5	3

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (4 + 5 + 5) / 3 = 14 / 3 = 4.67 units

Average Waiting Time = (0 + 2 + 3) / 3 = 5 / 3 = 1.67 units

Question 2

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	1	5
P2	2	3
P3	3	6

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	1	5	6	5	0
P2	2	3	9	7	4
P3	3	6	15	12	6

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (5 + 7 + 12) / 3 = 24 / 3 = 8 units

Average Waiting Time = (0 + 4 + 6) / 3 = 10 / 3 = 3.33 units

Question 3

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	1	2
P2	3	4
P3	5	3
P4	6	2

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	1	2	3	2	0
P2	3	4	7	4	0
P3	5	3	10	5	2
P4	6	2	12	6	4

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (2 + 4 + 5 + 6) / 4 = 17 / 4 = 4.25 units

Average Waiting Time = (0 + 0 + 2 + 4) / 4 = 6 / 4 = 1.5 units

Question 4

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	4
P2	1	3
P3	2	1
P4	3	2

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	4	4	4	0
P2	1	3	7	6	3
P3	2	1	8	6	5
P4	3	2	10	7	5

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (4 + 6 + 6 + 7) / 4 = 23 / 4 = 5.75 units

Average Waiting Time = (0 + 3 + 5 + 5) / 4 = 13 / 4 = 3.25 units

Question 5

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	2	3
P2	4	1
P3	6	2
P4	7	4

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	2	3	5	3	0
P2	4	1	6	2	1
P3	6	2	8	2	0
P4	7	4	12	5	1

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (3 + 2 + 2 + 5) / 4 = 12 / 4 = 3 units

Average Waiting Time = (0 + 1 + 0 + 1) / 4 = 2 / 4 = 0.5 units

Question 6

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	6
P2	2	3
P3	4	5
P4	6	2

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	6	6	6	0
P2	2	3	9	7	4
P3	4	5	14	10	5
P4	6	2	16	10	8

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (6 + 7 + 10 + 10) / 4 = 33 / 4 = 8.25 units

Average Waiting Time = (0 + 4 + 5 + 8) / 4 = 17 / 4 = 4.25 units

Question 7

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	7
P2	1	5
P3	2	3

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	7	7	7	0
P2	1	5	12	11	6
P3	2	3	15	13	10

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (7 + 11 + 13) / 3 = 31 / 3 = 10.33 units

Average Waiting Time = (0 + 6 + 10) / 3 = 16 / 3 = 5.33 units

Question 8

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	3	2
P2	5	4
P3	7	3
P4	9	1

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	3	2	5	2	0
P2	5	4	9	4	0
P3	7	3	12	5	2
P4	9	1	13	4	3

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (2 + 4 + 5 + 4) / 4 = 15 / 4 = 3.75 units

Average Waiting Time = (0 + 0 + 2 + 3) / 4 = 5 / 4 = 1.25 units

Question 9

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	4
P2	1	5
P3	3	3
P4	5	2

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	4	4	4	0
P2	1	5	9	8	3
P3	3	3	12	9	6
P4	5	2	14	9	7

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (4 + 8 + 9 + 9) / 4 = 30 / 4 = 7.5 units

Average Waiting Time = (0 + 3 + 6 + 7) / 4 = 16 / 4 = 4 units

Question 10

find the average Turn Around Time and Waiting Time of following processes using FCFS(FIRST COME FIRST SERVED) process scheduling algorithm?

Process	Arrival Time	Burst Time
P1	0	2
P2	2	4
P3	4	3
P4	5	1

Solution

Formulas:

• Turn Around Time (TAT) = Completion Time (CT) - Arrival Time (AT)
• Waiting Time (WT) = Turn Around Time (TAT) - Burst Time (BT)

Gantt Chart

Process	Arrival Time	Burst Time	Completion Time	Turn Around Time	Waiting Time
P1	0	2	2	2	0
P2	2	4	6	4	0
P3	4	3	9	5	2
P4	5	1	10	5	4

Formulas:

• Average Turn Around Time (Average TAT) = Σ(TAT) / Number of Processes
• Average Waiting Time (Average WT) = Σ(WT) / Number of Processes

Average Turn Around Time = (2 + 4 + 5 + 5) / 4 = 16 / 4 = 4 units

Average Waiting Time = (0 + 0 + 2 + 4) / 4 = 6 / 4 = 1.5 units