Question Details

Maximize Z = 7x + 11y, subject to 3x + 5y ≤ 26, 5x + 3y ≤ 30, x ≥ 0, y ≥ 0

Options

A

59 at (9/2, 5/2)

B

42 at (6, 0)

C

49 at (7, 0)

D

57.2 at (0, 5.2)

Correct Answer :

59 at (9/2, 5/2)

Solution :

The correct option is 59 at (9/2, 5/2).

To find the maximum value of the objective function Z=7x+11y subject to the given linear constraints, we can determine the corner points of the feasible region.

The constraints are given by:
1) 3x+5y26
2) 5x+3y30
3) x0,y0

Let us find the boundary lines and their intersection points with the coordinate axes in the first quadrant:
For the line 3x+5y=26:
When x=0, y=265=5.2. So, the y-intercept is (0,5.2).
When y=0, x=263. So, the x-intercept is (263,0).

For the line 5x+3y=30:
When x=0, y=10. So, the y-intercept is (0,10).
When y=0, x=6. So, the x-intercept is (6,0).

Next, we find the point of intersection of the two lines by solving the system of linear equations:
Multiply the first equation 3x+5y=26 by 3:
9x+15y=78
Multiply the second equation 5x+3y=30 by 5:
25x+15y=150

Subtract the first modified equation from the second:
(25x-9x)=150-78
16x=72
x=7216=92=4.5

Substitute x=92 back into 3x+5y=26:
3(92)+5y=26
272+5y=26
5y=26-13.5=12.5
y=12.55=2.5=52

Thus, the intersection point of the two constraint lines is (92,52).

The corner points of the feasible region defined by the system of linear inequalities are:
1) (0,0)
2) (6,0) (from the boundary 5x+3y30)
3) (0,5.2) (from the boundary 3x+5y26)
4) (92,52) (the intersection of the boundary lines)

Now, we evaluate the objective function Z=7x+11y at each corner point:
- At (0,0): Z=7(0)+11(0)=0
- At (6,0): Z=7(6)+11(0)=42
- At (0,5.2): Z=7(0)+11(5.2)=57.2
- At (92,52):
Z=7(92)+11(52)=632+552=1182=59

Comparing these values, the maximum value of Z is 59, which occurs at the point (92,52).

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