| Exam Board | Edexcel |
|---|---|
| Module | FD1 AS (Further Decision 1 AS) |
| Year | 2024 |
| Session | June |
| Marks | 12 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Linear Programming |
| Type | Reverse engineering constraints from graph |
| Difficulty | Standard +0.3 This is a standard linear programming question requiring students to read constraints from a graph, write verbal constraints as inequalities, add them to a diagram, and use the objective line method. While it involves multiple parts and careful graphical work, all techniques are routine for Further Maths Decision students with no novel problem-solving required. The reverse-engineering aspect in part (a) is straightforward reading from clearly marked lines. |
| Spec | 7.06a LP formulation: variables, constraints, objective function7.06b Slack variables: converting inequalities to equations7.06d Graphical solution: feasible region, two variables |
| Candidate surname | Other names | |||||||
| Centre Number | Candidate Number | |||||||
| □ | □ | |||||||
| VJYV SIHI NI JIIYM ION OC | V346 SIHI NI JLIYM ION OC | V34V SIHI NI IIIIM ION OC |
| VJYV SIHI NI JIIIM ION OC | V341 S1H1 NI JLIYM ION OA | V34V SIHI NI IIIVM ION OC |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| \(x + y \leq 30\) | M1 | One correct inequality in any form e.g. \(y - 2x - 10 \leq 0\). Condone strict inequality. Must be simplified to three terms only (coefficients need not be integers) |
| \(y \leq 2x + 10\) | A1 | Two correct inequalities in any form. Condone strict inequalities. Must be simplified to three terms only |
| \(5y \geq 2x - 10\) | A1 | All three inequalities correct with three terms and integer coefficients. Must not be strict inequalities |
| (3) | SC: M1A0A0 for two correct "equations" with \(=\) or inequality reversed. Graph does NOT show \(x \geq 0\) and \(y \geq 0\) so these will not be accepted |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| \(y \geq 1\) | B1 | Any one of \(y \geq x - 10\) or \(y \leq 5x\) in any form (accept strict inequalities) |
| \(y + 10 \geq x\) | B1 | All three correct in any form. Must not be strict inequalities |
| \(y \leq 5x\) | ||
| (2) |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| One line drawn with gradient 1 or gradient 5 (or \(\frac{1}{5}\)) | M1 | Condone dashed line |
| Either \(y \geq x - 10\) or \(y \leq 5x\) drawn correctly with correct shading | A1ft | ft their stated inequalities from (b), allow recovery. Condone dashed line |
| All three correct inequalities drawn correctly with solid lines, correct region \(R\) labelled | A1 | CAO. Penalise poorly drawn lines. Accuracy within 1 small square. \(y \geq x-10\) passes through \((10,0)\) and \((20,10)\). \(y \leq 5x\) passes through \((0,0)\) and \((5,25)\) |
| (3) |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| Objective line drawn \(3x + 5y = \text{constant}\) \(\left(m = \frac{-3}{5}\right)\) | M1 | Drawn accurately, parallel to line passing through \((0,6)\) and \((10,0)\). Accuracy within 1 small square. Minimum passing through \((0,3)\) and \((5,0)\). Accept reciprocal gradient for M mark only |
| Optimal point \(\left(\frac{20}{3}, \frac{70}{3}\right)\) | A1 | Accept \(x = \frac{20}{3}\) and \(y = \frac{70}{3}\) |
| (2) |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Marks | Guidance |
| Consideration of integer coordinates around the optimal vertex | dM1 | Dependent on 1st M1 and correct objective line. Must have tested at least two of \((6,23)\), \((6,24)\), \((7,23)\) and \((7,24)\) |
| 7 orange fish and 23 blue fish; Total value \(3(7) + 5(23) = \text{£}136\) | A1 | CAO. Clear statement including 7 orange (fish) and 23 blue (fish) and total value £136 |
| (4) | Integer points: \((6,23)\to133\), \((6,24)\to138\)✗, \((7,23)\to136\)✓, \((7,24)\to141\)✗ |
## Question 4:
---
### Part 4(a):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $x + y \leq 30$ | M1 | One correct inequality in any form e.g. $y - 2x - 10 \leq 0$. Condone strict inequality. Must be simplified to three terms only (coefficients need not be integers) |
| $y \leq 2x + 10$ | A1 | Two correct inequalities in any form. Condone strict inequalities. Must be simplified to three terms only |
| $5y \geq 2x - 10$ | A1 | All three inequalities correct with three terms and integer coefficients. Must **not** be strict inequalities |
| | **(3)** | SC: M1A0A0 for two correct "equations" with $=$ or inequality reversed. Graph does NOT show $x \geq 0$ and $y \geq 0$ so these will not be accepted |
---
### Part 4(b):
| Answer/Working | Marks | Guidance |
|---|---|---|
| $y \geq 1$ | B1 | Any one of $y \geq x - 10$ or $y \leq 5x$ in any form (accept strict inequalities) |
| $y + 10 \geq x$ | B1 | All three correct in any form. Must **not** be strict inequalities |
| $y \leq 5x$ | | |
| | **(2)** | |
---
### Part 4(c):
| Answer/Working | Marks | Guidance |
|---|---|---|
| One line drawn with gradient 1 or gradient 5 (or $\frac{1}{5}$) | M1 | Condone dashed line |
| Either $y \geq x - 10$ or $y \leq 5x$ drawn correctly with correct shading | A1ft | ft their stated inequalities from (b), allow recovery. Condone dashed line |
| All three correct inequalities drawn correctly with solid lines, correct region $R$ labelled | A1 | CAO. Penalise poorly drawn lines. Accuracy within 1 small square. $y \geq x-10$ passes through $(10,0)$ and $(20,10)$. $y \leq 5x$ passes through $(0,0)$ and $(5,25)$ |
| | **(3)** | |
---
### Part 4(d)(i):
| Answer/Working | Marks | Guidance |
|---|---|---|
| Objective line drawn $3x + 5y = \text{constant}$ $\left(m = \frac{-3}{5}\right)$ | M1 | Drawn accurately, parallel to line passing through $(0,6)$ and $(10,0)$. Accuracy within 1 small square. Minimum passing through $(0,3)$ and $(5,0)$. Accept reciprocal gradient for M mark only |
| Optimal point $\left(\frac{20}{3}, \frac{70}{3}\right)$ | A1 | Accept $x = \frac{20}{3}$ and $y = \frac{70}{3}$ |
| | **(2)** | |
---
### Part 4(d)(ii):
| Answer/Working | Marks | Guidance |
|---|---|---|
| Consideration of integer coordinates around the optimal vertex | dM1 | Dependent on 1st M1 and correct objective line. Must have tested at least two of $(6,23)$, $(6,24)$, $(7,23)$ and $(7,24)$ |
| 7 orange fish and 23 blue fish; Total value $3(7) + 5(23) = \text{£}136$ | A1 | CAO. Clear statement including 7 orange (fish) and 23 blue (fish) and total value £136 |
| | **(4)** | Integer points: $(6,23)\to133$, $(6,24)\to138$✗, $(7,23)\to136$✓, $(7,24)\to141$✗ |
**(12 marks total)**
4.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{ca57c64b-0b33-4179-be7f-684bd6ea2162-07_1105_1249_312_512}
\captionsetup{labelformat=empty}
\caption{Figure 4}
\end{center}
\end{figure}
Figure 4 shows three of the six constraints for a linear programming problem in $x$ and $y$ The unshaded region and its boundaries satisfy these three constraints.
\begin{enumerate}[label=(\alph*)]
\item State these three constraints as simplified inequalities with integer coefficients.
The variables $x$ and $y$ represent the number of orange fish and the number of blue fish, respectively, that are to be kept in an aquarium.
The number of fish in the aquarium is subject to these three further constraints
\begin{itemize}
\item there must be at least one blue fish
\item the orange fish must not outnumber the blue fish by more than ten
\item there must be no more than five blue fish for every orange fish
\item Write each of these three constraints as a simplified inequality with integer coefficients.
\item Represent these three constraints by adding lines and shading to Diagram 1 in the answer book, labelling the feasible region, $R$
\end{itemize}
The total value (in pounds) of the fish in the aquarium is given by the objective function
$$\text { Maximise } P = 3 x + 5 y$$
\item \begin{enumerate}[label=(\roman*)]
\item Use the objective line method to determine the optimal point of the feasible region, giving its coordinates as exact fractions.
\item Hence find the maximum total value of the fish in the aquarium, stating the optimal number of orange fish and the optimal number of blue fish.
\begin{table}[h]
\begin{center}
\captionsetup{labelformat=empty}
\caption{Please check the examination details below before entering your candidate information}
\begin{tabular}{|l|l|l|l|l|l|l|l|l|}
\hline
\multicolumn{8}{|c|}{Candidate surname} & Other names \\
\hline
\multicolumn{4}{|l|}{Centre Number} & \multicolumn{4}{|l|}{Candidate Number} & \\
\hline
□ & & & □ & & & & & \\
\hline
\end{tabular}
\end{center}
\end{table}
\section*{Pearson Edexcel Level 3 GCE}
\section*{Friday 17 May 2024}
Afternoon
\section*{Further Mathematics}
Advanced Subsidiary\\
Further Mathematics options\\
27: Decision Mathematics 1\\
(Part of options D, F, H and K)
\section*{D1 Answer Book}
Do not return the question paper with the answer book.\\
1.\\
$\begin{array} { l l l l l l l l l l l } 4 & 6.5 & 7 & 1.3 & 2 & 5 & 1.5 & 6 & 4.5 & 6 & 1 \end{array}$
2.
\begin{center}
\includegraphics[max width=\textwidth, alt={}]{ca57c64b-0b33-4179-be7f-684bd6ea2162-12_435_815_392_463}
\end{center}
\section*{Diagram 1}
Use this diagram only if you need to redraw your activity network.\\
\includegraphics[max width=\textwidth, alt={}, center]{ca57c64b-0b33-4179-be7f-684bd6ea2162-12_442_820_2043_458}
Copy of Diagram 1
\begin{center}
\begin{tabular}{|l|l|l|}
\hline
VJYV SIHI NI JIIYM ION OC & V346 SIHI NI JLIYM ION OC & V34V SIHI NI IIIIM ION OC \\
\hline
\hline
\end{tabular}
\end{center}
Key:
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{ca57c64b-0b33-4179-be7f-684bd6ea2162-13_1217_1783_451_236}
\captionsetup{labelformat=empty}
\caption{Diagram 2}
\end{center}
\end{figure}
3.\\
\includegraphics[max width=\textwidth, alt={}, center]{ca57c64b-0b33-4179-be7f-684bd6ea2162-14_2463_1240_339_465}\\
Shortest route from A to M:\\
Length of shortest route from A to M:\\
\begin{center}
\includegraphics[max width=\textwidth, alt={}]{ca57c64b-0b33-4179-be7f-684bd6ea2162-16_3038_2264_0_0}
\end{center}
\begin{center}
\includegraphics[max width=\textwidth, alt={}]{ca57c64b-0b33-4179-be7f-684bd6ea2162-17_1103_1247_397_512}
\end{center}
\section*{Diagram 1}
\section*{There is a copy of Diagram 1 on page 11 if you need to redraw your graph.}
\begin{center}
\begin{tabular}{|l|l|l|}
\hline
VJYV SIHI NI JIIIM ION OC & V341 S1H1 NI JLIYM ION OA & V34V SIHI NI IIIVM ION OC \\
\hline
\hline
\end{tabular}
\end{center}
Use this diagram only if you need to redraw your graph.\\
\includegraphics[max width=\textwidth, alt={}, center]{ca57c64b-0b33-4179-be7f-684bd6ea2162-19_1108_1252_1606_509}
Copy of Diagram 1
\end{enumerate}\end{enumerate}
\hfill \mbox{\textit{Edexcel FD1 AS 2024 Q4 [12]}}