D2 6th June 2013

well technically = as you will deliver all your stock to meet the demand.

However, you will get away with <= on all transportation questions.

Okay... I've just noticed something glaringly obvious which should settle this. First, this is the solution laid out by example 12 page 27:

Let be the number of units transported from $i$ to $j$.

Minimise

Subject to:








Okay? So, why don't I just set all the ? This satisfies all constraints and clearly gives the minimum value of C.

Unless of course, I'm missing something (which for me is quite likely).

Thanks. Also, about the question above, say you had an unbalanced problem, then setting xij=0 seems to be the best solution when this obviously isn't the case. Do you know why that is?

Hi Arsey, could you please explain this?

ok , i got a quick question, when writing a maximizing allocation problem as a linear progamming problem, u first transform the matrix and then continue as normal, so would the objective be to maximise or minimise, i looked on the example of the book on page 55 , and this one is minimising and i am not sure it it is right?

Xij is the amount you are transporting from (factory) i to (shop) j

You wouldn't have a very good business if you didn't transport anything!

If the supply is enough you have to satisfy the demand and you are trying to minimise the costs of doing that. You cannot just say I am going to minimise my costs by not delivering anything to anyone.

So say you have 3 lines on the well graph for each strategy for B.

If the best mixed strategy for A is where B1 and B2 meet and if B knows that A
is playing the best mixed strategy then there is no point B playing 3 as he will lose more (or gain less); therefore you can delete column B3 from the game which reduces it to a 2x2 matrix

But say you used simplex to solve it, would it not give Xij=0 as the optimal solution?

As far as i remember one of the arrows was in the wrong direction (which you can see by applying flow conservation) and this gave a completely wrong answer chances are that your answer is correct

I'm not looking at it right now, but beware that mark schemes for mock papers and practice papers are generally very wrong. I do recall remembering that the mark scheme was wrong when labelling some arrows on one of those papers.



Yes possibly, June 2008 was part of the current spec as far as I know. It is pretty much the same idea anyway, so I don't see why they couldn't ask. Although I can't say I remember being asked to use Prim's, usually they ask you to use Kruskal's but either way, you should be comfortable with both.



As you're filling the table in, if supply and demand are satisfied at the same time, you can either go across one and put the 0 in the cell, then move down. Or, go down and put the 0 in that cell, and move along one. Basically in the diagonal you have, you want to put the zero in one of the spaces where normally you'd expect a number.

Technically you can actually put it anywhere, but it's best to stick to the rule of moving along and downwards only.



64 if I am not mistaken

probably, there were quite a few errors on the mock paper.

Xij is the amount you are transporting from (factory) i to (shop) j

You wouldn't have a very good business if you didn't transport anything!

If the supply is enough you have to satisfy the demand and you are trying to minimise the costs of doing that. You cannot just say I am going to minimise my costs by not delivering anything to anyone.

the last question was a bugger, hated it, well there goes my A , that question was really different from the ones from the past papers , most people who finished it at my school got around 32000

I got 29000