Q9 of 31 Page 519

A diet is to contain at least 80 units of vitamin A and 100 units of minerals. Two foods F1 and F2 are available. Food F1 costs Rs 4 per unit food and F2 costs Rs 6 per unit. One unit of food F1 contains 3 units of vitamin A and 4 units of minerals. One unit of food F2 contains 6 units of vitamin A and 3 units of minerals. Formulate this as a linear programming problem. Find the minimum cost for diet that consists of mixture of these two foods and also meets the minimal nutritional requirements.

let the diet contain x units of food F1 and y units of food F2.

x and y ≥ 0


The tabular representation of the data is



The cost of food F1 is Rs 4/unit and the cost of food F2 is Rs 6 per unit.


The constraints here are


3x + 6y ≥ 80


4x+ 3y ≥ 100


x and y ≥ 0


Total cost of the diet Z= 4x+ 6y


The mathematical formulation of the given data is


maximize Z= 4x+ 6y


Subject to constraints


3x + 6y ≥ 80


4x+ 3y ≥ 100


x and y ≥ 0


the feasible region by the system of constraints is as follows:



It can be seen the feasible region is unbounded with


The corner points of the feasible region are A(


The values of Z at the corner points are



As the feasible region is unbounded therefore 104 may or may not be the minimum value of Z.


For this we will draw a graph of inequality 4x+ 6y < 104


It can be seen that the feasible region has no common points with 4x+ 6y < 104


the maximum cost of the mixture will be Rs104.


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The corner points of the feasible region determined by the following system of linear inequalities:

2x + y ≤ 10, x + 3y ≤ 15, x, y ≥ 0 are (0, 0), (5, 0), (3, 4) and (0, 5). Let


Z = px + qy, where p, q > 0. Condition on p and q so that the maximum of Z occurs at both (3, 4) and (0, 5) is


A. p =q B. p = 2q


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