Site navigation

Food X contains 6 units of Vitamin D per gram and 7 units of Vitamin E per gram and cost is Rs 12 per…

For a primal problem "minimise \(c^T x\) subject to \(Ax \ge b\), \(x \ge 0\)", the dual is "maximise \(b^T u\) subject to \(A^T u \le c\), \(u \ge 0\)". Here b = (100, 120)…

Choose your answer

Food X contains 6 units of Vitamin D per gram and 7 units of Vitamin E per gram and cost is Rs 12 per gram. Food Y contains 8 units of vitamin D per gram and 12 units of Vitamin E per gram and cost is Rs 20 per gram. The daily minimum requirements of vitamin D and E are 100 units and 120 units respectively. Suppose x is quantity (in gram) of food X, y is quantity (in gram) of food Y. Answering the following question based on the above paragraph given.

The dual of the formulated LPP is :

Select one answer
Answer and explanation

Correct answer A

For a primal problem "minimise cTxc^T x subject to Ax≥bAx \ge b, x≥0x \ge 0", the dual is "maximise bTub^T u subject to ATu≤cA^T u \le c, u≥0u \ge 0". Here b = (100, 120) and c = (12, 20), and the columns of the primal give 6u+7v≤126u + 7v \le 12 and 8u+12v≤208u + 12v \le 20, with u,v≥0u, v \ge 0. The dual optimum u = 1/4, v = 3/2 gives 100×0.25+120×1.5=205100 \times 0.25 + 120 \times 1.5 = 205, equal to the primal minimum, which confirms the formulation; unrestricted dual variables or ≥ constraints do not fit this primal.

Practice for these exams

  • UGC NET Computer Science and Applications

Related question papers

Related exam syllabi

Related questions in this topic