AQA D2 2009 June — Question 6

Exam BoardAQA
ModuleD2 (Decision Mathematics 2)
Year2009
SessionJune
TopicNetwork Flows

6 [Figures 3, 4 and 5, printed on the insert, are provided for use in this question.]
The network shows a system of pipes with the lower and upper capacities for each pipe in litres per second.
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  1. Find the value of the cut \(C\).
  2. Figure 3, on the insert, shows a partially completed diagram for a feasible flow of 40 litres per second from \(S\) to \(T\). Indicate, on Figure 3, the flows along the edges \(A E , E F\) and \(F G\).
    1. Taking your answer from part (b) as an initial flow, indicate potential increases and decreases of the flow along each edge on Figure 4.
    2. Use flow augmentation on Figure 4 to find the maximum flow from \(S\) to \(T\). You should indicate any flow augmenting paths in the table and modify the potential increases and decreases of the flow on the network.
  3. Illustrate the maximum flow on Figure 5.
  4. Find a cut with value equal to that of the maximum flow.