Consider the linear programming problem (LPP): Maximize $Z = 6x + 3y$ subject to the conditions, $4x + y ≥80, x+5y ≥ 115, 3x + 2y ≤ 150, x, y ≥ 0$. In reference to the above LPP, which of the following are correct? (A) The feasible region is bounded. Choose the correct answer from the options given below: |
(A), (B) and (D) only (A), (B) and (C) only (A) and (C) only (B) and (D) only |
(A) and (C) only |
The correct answer is Option (3) → (A) and (C) only $\text{Constraints: }4x+y\ge 80,\ x+5y\ge 115,\ 3x+2y\le 150,\ x\ge0,\ y\ge0$ Intersection of pairs (equalities): $4x+y=80,\ x+5y=115 \Rightarrow (x,y)=(15,20)$ $4x+y=80,\ 3x+2y=150 \Rightarrow (x,y)=(2,72)$ $x+5y=115,\ 3x+2y=150 \Rightarrow (x,y)=(40,15)$ Check feasibility of these points (they satisfy all inequalities): $(15,20):\ 4(15)+20=80,\ 15+5(20)=115,\ 3(15)+2(20)=85\le150$ $(2,72):\ 4(2)+72=80,\ 2+5(72)=362,\ 3(2)+2(72)=150$ $(40,15):\ 4(40)+15=175,\ 40+5(15)=115,\ 3(40)+2(15)=150$ $\text{Feasible region is the triangle with vertices }(15,20),(2,72),(40,15)\text{, so it is bounded. (A is true)}$ Evaluate $Z=6x+3y$ at these vertices: $Z(15,20)=6(15)+3(20)=150$ $Z(2,72)=6(2)+3(72)=228$ $Z(40,15)=6(40)+3(15)=285$ Maximum value $=285$ at $(40,15)$, so (C) is true. Statement (B) is false because $(0,75)$ is not a feasible corner (it fails $4x+y\ge80$). Statement (D) is false because an optimal solution exists (maximum $285$). Correct options: (A) and (C) |