Machine-translated by Google. Questions are authored in English.
Top

Discussion

Consider the transportation problem

Min. \(z = \sum_{i=1}^{m}\sum_{j=1}^{n} c_{ij}x_{ij}\)

Subject to :
\(\sum_{j=1}^{n} x_{ij} = a_{i}, i = 1, 2, ....., m,\)
\(\sum_{i=1}^{m} x_{ij} = b_{j}, j = 1, 2, ....., n\) and \(x_{ij} \ge 0\)

The existence of a feasible solution of the transportation problem is possible :

(I) if \(\sum_{i=1}^{m} a_{i} = \sum_{j=1}^{n} b_{j}\)
(II) if and only if \(\sum_{i=1}^{m} a_{i} = \sum_{j=1}^{n} b_{j}\)

Then which of the following is true ?

  • A.Only (I) is true
  • B.Only (II) is true
  • C.Both are true
  • D.None of them is true

Answer: C

Both statements are true.

If total supply equals total demand, a feasible solution always exists: for example \(x_{ij} = a_{i}b_{j}/T\) with \(T = \sum a_{i} = \sum b_{j}\) satisfies every row and column constraint and is non-negative. So (I) holds.

Conversely, with equality constraints, summing all row constraints gives \(\sum\sum x_{ij} = \sum a_{i}\) and summing all column constraints gives \(\sum\sum x_{ij} = \sum b_{j}\), so a feasible solution forces \(\sum a_{i} = \sum b_{j}\). Hence the condition is necessary as well as sufficient, and (II) holds too.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.