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Further Maths · AQA 7367 · Paper 3 Discrete · June 2023

AQA A Level Further Maths Paper 3 Discrete June 2023 question paper

AQA 7367 · Paper 3 Discrete

9 questions
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Question 1

The simple-connected graph G is shown below.

Figure for question 1

The graph G has n faces.

State the value of n

Circle your answer.

2 3 4 5

[1 mark]

Answer
Mark scheme for question 1

Question 2

Figure for question 2

[1 mark]

Answer
Mark scheme for question 2

Question 3

A student is solving a maximising linear programming problem.

The graph below shows the constraints, feasible region and objective line for the student’s linear programming problem.

Figure for question 3

Which vertex is the optimal vertex?

Circle your answer.

A B C D

[1 mark]

Answer
Mark scheme for question 3

Question 4

The network below represents a system of water pipes in a geothermal power station.

The numbers on each arc represent the lower and upper capacity for each pipe in gallons per second.

Figure for question 4

The water is taken from a nearby river at node A The water is then pumped through the system of pipes and passes through one of three treatment facilities at nodes H, I and J before returning to the river.

(a)

The senior management at the power station want all of the water to undergo a final quality control check at a new facility before it returns to the river.

Using the language of networks, explain how the network above could be modified to include the new facility.

[2 marks]

Answer
Mark scheme for question 4(a)
(b)

Find the value of the cut { A, B, C, D, E } { F, G, H, I, J }

[1 mark]

Answer
Mark scheme for question 4(b)
(c)

Tim, a trainee engineer at the power station, correctly calculates the value of the cut { A, B, C, D, E, F } { G, H, I, J } to be 106 gallons per second.

Tim then claims that the maximum flow through the network of pipes is 106 gallons per second.

Comment on the validity of Tim’s claim.

[2 marks]

Answer
Mark scheme for question 4(c)

Question 5

A student is solving the following linear programming problem.

Question 5, shown as an image
(a)

The student wants to use the simplex algorithm to solve the linear programming problem.

They modify the linear programming problem by introducing the objective function

Question 5, shown as an image

and the slack variables r and s

State one further modification that must be made to the linear programming problem so that it can be solved using the simplex algorithm.

[1 mark]

Answer
Mark scheme for question 5(a)
(b)(i)

Complete the initial simplex tableau for the modified linear programming problem.

Figure for question 5

[2 marks]

Answer
Mark scheme for question 5(b)(i)
(b)(ii)

Hence, perform one iteration of the simplex algorithm.

Figure for question 5

[2 marks]

Answer
Mark scheme for question 5(b)(ii)
(c)
Figure for question 5
(c)(i)

Explain how the student can tell that the optimal solution to the modified linear programming problem can be determined from the above simplex tableau.

[1 mark]

Answer
Mark scheme for question 5(c)(i)
(c)(ii)

Find the optimal solution of the original linear programming problem.

[2 marks]

Answer
Mark scheme for question 5(c)(ii)

Question 6

Figure for question 6
(a)

The gritter truck starts gritting the roads at 7:00 pm and moves with an average speed of 5 metres per second during its journey.

Find the earliest time for the gritter truck to have gritted each road at least once and arrived back at the junction it started from, giving your answer to the nearest minute.

Fully justify your answer.

[6 marks]

Answer
Mark scheme for question 6(a)
(b)

Explain how a refinement to the council’s requirement, that the gritter truck must start and finish at the same junction, could reduce the time taken to grit all of the roads at least once.

[2 marks]

Answer
Mark scheme for question 6(b)

Question 7

Figure for question 7
(a)
(a)(i)

Find the earliest start time and the latest finish time for each activity and write these values on the activity network in Figure 1

[2 marks]

Answer
Mark scheme for question 7(a)(i)
(a)(ii)

Write down the critical path.

[1 mark]

Answer
Mark scheme for question 7(a)(ii)
(b)

On Figure 2 below, draw a cascade diagram (Gantt chart) for the planned building project, assuming that each activity starts as early as possible.

Figure for question 7

[3 marks]

Answer
Mark scheme for question 7(b)
(c)

During further planning of the building project, Nova Merit Construction find that activity F is not necessary and they remove it from the project.

Explain the effect removing activity F has on the minimum completion time of the project.

[2 marks]

Answer
Mark scheme for question 7(c)

Question 8

The graph G is shown below.

Figure for question 8
(a)
(a)(i)

State, with a reason, whether or not G is simple.

[2 marks]

Answer
Mark scheme for question 8(a)(i)
(a)(ii)

A student states that G is Eulerian.

Explain why the student is correct.

[2 marks]

Answer
Mark scheme for question 8(a)(ii)
(b)

The graph H has 8 vertices with degrees 2, 2, 4, 4, 4, 4, 4 and 4

Comment on whether H is isomorphic to G

[2 marks]

Answer
Mark scheme for question 8(b)
(c)

The formula v maths symbol e maths symbol f maths symbol 2, where

Question 8, shown as an image

can be used with graphs which satisfy certain conditions.

Prove that G does not satisfy the conditions for the above formula to apply.

[3 marks]

Answer
Mark scheme for question 8(c)

Question 9

The group (C, maths symbol4) contains the elements 0, 1, 2 and 3

(a)
(a)(i)

Show that C is a cyclic group.

[2 marks]

Answer
Mark scheme for question 9(a)(i)
(a)(ii)

State the group of symmetries of a regular polygon that is isomorphic to C

[1 mark]

Answer
Mark scheme for question 9(a)(ii)
(b)

The group (V, maths symbol) contains the elements (1, 1), (1, maths symbol1), (maths symbol1, 1) and (maths symbol1, maths symbol1)

The binary operation maths symbol between elements of V is defined by

Question 9, shown as an image
(b)(i)

Find the element in V that is the inverse of (maths symbol1, 1)

Fully justify your answer.

[2 marks]

Answer
Mark scheme for question 9(b)(i)
(b)(ii)

Determine, with a reason, whether or not C maths symbol V

[2 marks]

Answer
Mark scheme for question 9(b)(ii)
(c)

The group G has order 16

Rachel claims that as 1, 2, 4, 8 and 16 are the only factors of 16 then, by Lagrange’s theorem, the group G will have exactly 5 distinct subgroups, including the trivial subgroup and G itself.

Comment on the validity of Rachel’s claim.

[2 marks]

Answer
Mark scheme for question 9(c)

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