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For the LPP: minimize z=6x+3yz = 6x + 3y subject to the constraints

4x+y≥804x + y \geq 80

x+5y≥115x + 5y \geq 115

3x+2y≤1503x + 2y \leq 150

x≥0,y≥0x \geq 0, y \geq 0 then the minimum value of z is

Solution

✅ Correct Option: 1

For the LPP: minimize z=6x+3yz = 6x + 3y subject to the constraints:

4x+y≥804x + y \geq 80

x+5y≥115x + 5y \geq 115

3x+2y≤1503x + 2y \leq 150

x≥0,y≥0x \geq 0, y \geq 0

The minimum value occurs at a corner point of the feasible region.


Finding the intersection of 4x+y=804x + y = 80 and x+5y=115x + 5y = 115:

y=80−4xy = 80 - 4x

x+5(80−4x)=115x + 5(80 - 4x) = 115

x+400−20x=115x + 400 - 20x = 115

−19x=−285-19x = -285

x=15x = 15

y=80−4(15)y = 80 - 4(15)

y=20y = 20

Corner point: (15,20)(15, 20)


Finding the intersection of 4x+y=804x + y = 80 and 3x+2y=1503x + 2y = 150:

y=80−4xy = 80 - 4x

3x+2(80−4x)=1503x + 2(80 - 4x) = 150

3x+160−8x=1503x + 160 - 8x = 150

−5x=−10-5x = -10

x=2x = 2

y=80−4(2)y = 80 - 4(2)

y=72y = 72

Corner point: (2,72)(2, 72)


Finding the intersection of x+5y=115x + 5y = 115 and 3x+2y=1503x + 2y = 150:

x=115−5yx = 115 - 5y

3(115−5y)+2y=1503(115 - 5y) + 2y = 150

345−15y+2y=150345 - 15y + 2y = 150

−13y=−195-13y = -195

y=15y = 15

x=115−5(15)x = 115 - 5(15)

x=40x = 40

Corner point: (40,15)(40, 15)


Evaluating z=6x+3yz = 6x + 3y at each corner point:

At (15,20)(15, 20):

z=6(15)+3(20)z = 6(15) + 3(20)

z=90+60z = 90 + 60

z=150z = 150

At (2,72)(2, 72):

z=6(2)+3(72)z = 6(2) + 3(72)

z=12+216z = 12 + 216

z=228z = 228

At (40,15)(40, 15):

z=6(40)+3(15)z = 6(40) + 3(15)

z=240+45z = 240 + 45

z=285z = 285


The minimum value of zz is 150150 at point (15,20)(15, 20).

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