D2 June 2007 Q3
3. To raise money for charity it is decided to hold a Teddy Bear making competition. Teams of four compete against each other to make 20 Teddy Bears as quickly as possible.
There are four stages: first cutting, then stitching, then filling and finally dressing.
Each team member can only work on one stage during the competition. As soon as a stage is completed on each Teddy Bear the work is passed immediately to the next team member.
The table shows the time, in seconds, taken to complete each stage of the work on one Teddy Bear by the members \(A\), \(B\), \(C\) and \(D\) of one of the teams.
| cutting | stitching | filling | dressing | |
|---|---|---|---|---|
| \(A\) | 66 | 101 | 85 | 36 |
| \(B\) | 66 | 98 | 74 | 38 |
| \(C\) | 63 | 97 | 71 | 34 |
| \(D\) | 67 | 102 | 78 | 35 |
Using the allocation found in (a),
| Scheme | Marks |
|---|---|
| \(\begin{bmatrix}66&101&85&36\\66&98&74&38\\63&97&71&34\\67&102&78&35\end{bmatrix}\) | |
| reducing rows first \(\begin{bmatrix}30&65&49&0\\28&60&36&0\\29&63&37&0\\32&67&43&0\end{bmatrix}\) then columns \(\begin{bmatrix}2&5&13&0\\0&0&0&0\\1&3&1&0\\4&7&7&0\end{bmatrix}\) (lines through row B and the dressing column) | M1 A1 |
| \(\begin{bmatrix}1&4&12&0\\0&0&0&1\\0&2&0&0\\3&6&6&0\end{bmatrix}\) (lines through rows B and C and the dressing column) | M1 A1ft A1ft |
| \(\begin{bmatrix}0&3&11&0\\0&0&0&2\\0&2&0&1\\2&5&5&0\end{bmatrix}\) | M1 A1ft A1ft |
| A – cutting B – stitching C – filling D – dressing | A1 |
| (9) |
Notes
The scheme shows the covering lines on the matrices; they are described in words here.
| Scheme | Marks |
|---|---|
| \(66 + 98 + 71 + 35 = 270\) seconds | B1 |
| (1) |
| Scheme | Marks |
|---|---|
| \(20 \times 98 + 66 + 71 + 35 = 2132\) seconds | M1 A1ft |
| = 35 minutes 32 seconds | A1 |
| (3) | |
| (13 marks) |