Graphical Method
LPP
Two products, namely P1 and P2 are being manufactured.
Each product has to be processed through two machines
M1 and M2. One unit of product P1 consumes 4 hours of
time on M1 and 2 hours of time on M2. Similarly, one unit
of P2 consumes 2 hours of time on M1 and 4 hours of
time on M2. 60 hours of time is available on M1 and 48
hours on M2. The per unit contribution margin of P1 is 8
and of P2 is 6. Determine the number of units of P1 and
P2 to be manufactured so as to maximise total
contribution.
Products M1 M2 Contribution
Margin
P1 4hrs 2hrs Rs.8
P2 2hrs 4hrs Rs.6
Total Machine
hours
60hrs 48hrs
𝑻𝒉𝒆 𝒂𝒃𝒐𝒗𝒆 𝒑𝒓𝒐𝒃𝒍𝒆𝒎 𝒄𝒂𝒏 𝒃𝒆 𝒇𝒐𝒓𝒎𝒖𝒍𝒂𝒕𝒆𝒅 𝒂𝒔:
𝑴𝒂𝒙𝒊𝒎𝒊𝒔𝒆 𝒛 = 𝟖𝒙 𝟏 + 𝟔𝒙 𝟐
𝒔𝒖𝒃𝒋𝒆𝒄𝒕 𝒕𝒐 𝒕𝒉𝒆 𝒄𝒐𝒏𝒔𝒕𝒓𝒂𝒊𝒏𝒕𝒔:
𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 ≤ 𝟔𝟎
𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 ≤ 𝟒𝟖
𝒙 𝟏 ≥ 𝟎
𝒙 𝟐 ≥ 𝟎
𝑷𝒍𝒐𝒕𝒕𝒊𝒏𝒈 𝒕𝒉𝒆 𝒕𝒘𝒐 𝒄𝒐𝒏𝒔𝒕𝒓𝒂𝒊𝒏𝒕𝒔, 𝒕𝒓𝒆𝒂𝒕𝒊𝒏𝒈 𝒕𝒉𝒆𝒎 𝒂𝒔 𝒔𝒕𝒓𝒊𝒄𝒕
𝒆𝒒𝒖𝒂𝒍𝒊𝒕𝒊𝒆𝒔:
𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 ≤ 𝟔𝟎
𝒐𝒓 𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 = 𝟔𝟎 … (𝒊)
𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 ≤ 𝟒𝟖
𝒐𝒓 𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 = 𝟒𝟖 … 𝒊𝒊
𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊 , 𝒍𝒆𝒕 𝒙 𝟏 = 𝟎
𝟒 × 𝟎 + 𝟐𝒙 𝟐 = 𝟔𝟎
𝒐𝒓 𝟎 + 𝟐𝒙 𝟐 = 𝟔𝟎
𝒐𝒓 𝟐𝒙 𝟐 = 𝟔𝟎
𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏:
𝒙 𝟐 =
𝟔𝟎
𝟐
𝒐𝒓 𝒙 𝟐 = 𝟑𝟎
∴ 𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊 = (𝟎, 𝟑𝟎)
𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊 , 𝒍𝒆𝒕 𝒙 𝟐 = 𝟎
𝟒𝒙 𝟏 + 𝟐 × 𝟎 = 𝟔𝟎
𝒐𝒓 𝟒𝒙 𝟏 + 𝟎 = 𝟔𝟎
𝒐𝒓 𝟒𝒙 𝟏 = 𝟔𝟎
𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏:
𝒙 𝟏 =
𝟔𝟎
𝟒
𝒐𝒓 𝒙 𝟏 = 𝟏𝟓
∴ 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊 = (𝟏𝟓, 𝟎)
𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊𝒊 , 𝒍𝒆𝒕 𝒙 𝟏 = 𝟎
𝟐 × 𝟎 + 𝟒𝒙 𝟐 = 𝟒𝟖
𝒐𝒓 𝟎 + 𝟒𝒙 𝟐 = 𝟒𝟖
𝒐𝒓 𝟒𝒙 𝟐 = 𝟒𝟖
𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏:
𝒙 𝟐 =
𝟒𝟖
𝟒
𝒐𝒓 𝒙 𝟐 = 𝟏𝟐
∴ 𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊𝒊 = (𝟎, 𝟏𝟐)
𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊𝒊 , 𝒍𝒆𝒕 𝒙 𝟐 = 𝟎
𝟐𝒙 𝟏 + 𝟒 × 𝟎 = 𝟒𝟖
𝒐𝒓 𝟐𝒙 𝟏 + 𝟎 = 𝟒𝟖
𝒐𝒓 𝟐𝒙 𝟏 = 𝟒𝟖
𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏:
𝒙 𝟏 =
𝟒𝟖
𝟐
𝒐𝒓 𝒙 𝟏 = 𝟐𝟒
∴ 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊𝒊 = 𝟐𝟒, 𝟎
𝑷𝒍𝒐𝒕𝒕𝒊𝒏𝒈 𝒕𝒉𝒆 𝒕𝒘𝒐 𝒍𝒊𝒏𝒆𝒔:
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
(𝟎, 𝟏𝟐)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
(𝟎, 𝟏𝟐)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
(𝟎, 𝟏𝟐)
(𝟐𝟒, 𝟎)
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
(𝟎, 𝟏𝟐)
(𝟐𝟒, 𝟎)
C
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30 35
(𝟎, 𝟑𝟎)
(𝟏𝟓, 𝟎)
A
B
(𝟎, 𝟏𝟐)
(𝟐𝟒, 𝟎)
C
Graphical method
Graphical method
Graphical method
Graphical method
Graphical method

Graphical method

  • 1.
  • 2.
    Two products, namelyP1 and P2 are being manufactured. Each product has to be processed through two machines M1 and M2. One unit of product P1 consumes 4 hours of time on M1 and 2 hours of time on M2. Similarly, one unit of P2 consumes 2 hours of time on M1 and 4 hours of time on M2. 60 hours of time is available on M1 and 48 hours on M2. The per unit contribution margin of P1 is 8 and of P2 is 6. Determine the number of units of P1 and P2 to be manufactured so as to maximise total contribution.
  • 3.
    Products M1 M2Contribution Margin P1 4hrs 2hrs Rs.8 P2 2hrs 4hrs Rs.6 Total Machine hours 60hrs 48hrs
  • 4.
    𝑻𝒉𝒆 𝒂𝒃𝒐𝒗𝒆 𝒑𝒓𝒐𝒃𝒍𝒆𝒎𝒄𝒂𝒏 𝒃𝒆 𝒇𝒐𝒓𝒎𝒖𝒍𝒂𝒕𝒆𝒅 𝒂𝒔: 𝑴𝒂𝒙𝒊𝒎𝒊𝒔𝒆 𝒛 = 𝟖𝒙 𝟏 + 𝟔𝒙 𝟐 𝒔𝒖𝒃𝒋𝒆𝒄𝒕 𝒕𝒐 𝒕𝒉𝒆 𝒄𝒐𝒏𝒔𝒕𝒓𝒂𝒊𝒏𝒕𝒔: 𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 ≤ 𝟔𝟎 𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 ≤ 𝟒𝟖 𝒙 𝟏 ≥ 𝟎 𝒙 𝟐 ≥ 𝟎
  • 5.
    𝑷𝒍𝒐𝒕𝒕𝒊𝒏𝒈 𝒕𝒉𝒆 𝒕𝒘𝒐𝒄𝒐𝒏𝒔𝒕𝒓𝒂𝒊𝒏𝒕𝒔, 𝒕𝒓𝒆𝒂𝒕𝒊𝒏𝒈 𝒕𝒉𝒆𝒎 𝒂𝒔 𝒔𝒕𝒓𝒊𝒄𝒕 𝒆𝒒𝒖𝒂𝒍𝒊𝒕𝒊𝒆𝒔: 𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 ≤ 𝟔𝟎 𝒐𝒓 𝟒𝒙 𝟏 + 𝟐𝒙 𝟐 = 𝟔𝟎 … (𝒊) 𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 ≤ 𝟒𝟖 𝒐𝒓 𝟐𝒙 𝟏 + 𝟒𝒙 𝟐 = 𝟒𝟖 … 𝒊𝒊
  • 6.
    𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊, 𝒍𝒆𝒕 𝒙 𝟏 = 𝟎 𝟒 × 𝟎 + 𝟐𝒙 𝟐 = 𝟔𝟎 𝒐𝒓 𝟎 + 𝟐𝒙 𝟐 = 𝟔𝟎 𝒐𝒓 𝟐𝒙 𝟐 = 𝟔𝟎 𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏: 𝒙 𝟐 = 𝟔𝟎 𝟐 𝒐𝒓 𝒙 𝟐 = 𝟑𝟎 ∴ 𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊 = (𝟎, 𝟑𝟎)
  • 7.
    𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊, 𝒍𝒆𝒕 𝒙 𝟐 = 𝟎 𝟒𝒙 𝟏 + 𝟐 × 𝟎 = 𝟔𝟎 𝒐𝒓 𝟒𝒙 𝟏 + 𝟎 = 𝟔𝟎 𝒐𝒓 𝟒𝒙 𝟏 = 𝟔𝟎 𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏: 𝒙 𝟏 = 𝟔𝟎 𝟒 𝒐𝒓 𝒙 𝟏 = 𝟏𝟓 ∴ 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊 = (𝟏𝟓, 𝟎)
  • 8.
    𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊𝒊, 𝒍𝒆𝒕 𝒙 𝟏 = 𝟎 𝟐 × 𝟎 + 𝟒𝒙 𝟐 = 𝟒𝟖 𝒐𝒓 𝟎 + 𝟒𝒙 𝟐 = 𝟒𝟖 𝒐𝒓 𝟒𝒙 𝟐 = 𝟒𝟖 𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏: 𝒙 𝟐 = 𝟒𝟖 𝟒 𝒐𝒓 𝒙 𝟐 = 𝟏𝟐 ∴ 𝒕𝒉𝒆 𝒇𝒊𝒓𝒔𝒕 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊𝒊 = (𝟎, 𝟏𝟐)
  • 9.
    𝑰𝒏 𝒆𝒒𝒖𝒂𝒕𝒊𝒐𝒏 𝒊𝒊, 𝒍𝒆𝒕 𝒙 𝟐 = 𝟎 𝟐𝒙 𝟏 + 𝟒 × 𝟎 = 𝟒𝟖 𝒐𝒓 𝟐𝒙 𝟏 + 𝟎 = 𝟒𝟖 𝒐𝒓 𝟐𝒙 𝟏 = 𝟒𝟖 𝒃𝒚 𝒄𝒓𝒐𝒔𝒔 − 𝒎𝒖𝒍𝒕𝒊𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏: 𝒙 𝟏 = 𝟒𝟖 𝟐 𝒐𝒓 𝒙 𝟏 = 𝟐𝟒 ∴ 𝒕𝒉𝒆 𝒔𝒆𝒄𝒐𝒏𝒅 𝒑𝒐𝒊𝒏𝒕 𝒐𝒏 𝒍𝒊𝒏𝒆 𝒊𝒊 = 𝟐𝟒, 𝟎 𝑷𝒍𝒐𝒕𝒕𝒊𝒏𝒈 𝒕𝒉𝒆 𝒕𝒘𝒐 𝒍𝒊𝒏𝒆𝒔:
  • 10.
  • 11.
  • 12.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎)
  • 13.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎)
  • 14.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎)
  • 15.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎)
  • 16.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A
  • 17.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B
  • 18.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B
  • 19.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B (𝟎, 𝟏𝟐)
  • 20.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B (𝟎, 𝟏𝟐)
  • 21.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B (𝟎, 𝟏𝟐) (𝟐𝟒, 𝟎)
  • 22.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B (𝟎, 𝟏𝟐) (𝟐𝟒, 𝟎) C
  • 23.
    0 5 10 15 20 25 30 35 0 5 1015 20 25 30 35 (𝟎, 𝟑𝟎) (𝟏𝟓, 𝟎) A B (𝟎, 𝟏𝟐) (𝟐𝟒, 𝟎) C