4MA0 Higher January 2012 Paper 4 Q22
22

Diagram NOT accurately drawn
\(OPQR\) is a rectangle.
\(D\) is the point on \(OP\) such that \(OD = \dfrac{1}{3}OP\).
\(E\) is the point on \(OQ\) such that \(OE = \dfrac{2}{3}OQ\).
\(PQF\) is the straight line such that \(QF = \dfrac{1}{3}PQ\).
\(\overrightarrow{OD} = \mathbf{a}\) \(\overrightarrow{OR} = 3\mathbf{b}\)
| Scheme | Marks |
|---|---|
| (i) \(3\mathbf{a} + 3\mathbf{b}\) oe | B1 |
| (ii) \(2\mathbf{a} + 2\mathbf{b}\) oe | B1 |
| (iii) \(\mathbf{a} + 2\mathbf{b}\) oe | B1 |
| (3) |
Notes
B1: Accept eg \(\frac{2}{3}(3\mathbf{a} + 3\mathbf{b})\)
B1: Accept eg \(2\mathbf{a} + 2\mathbf{b} - \mathbf{a}\)
Apart from Questions 3, 13(b) and 17(f) (where the mark scheme states otherwise), the correct answer, unless clearly obtained by an incorrect method, should be taken to imply a correct method.
| Scheme | Marks |
|---|---|
| \(\overrightarrow{DF} = 2\mathbf{a} + 4\mathbf{b}\) oe | M1 |
| \(\overrightarrow{DF} = 2\overrightarrow{DE}\) oe eg \(\overrightarrow{DE} = \overrightarrow{EF}\) | A1 |
| (2) | |
| (Total 5 marks) |
Notes
M1: Also award for \(\overrightarrow{EF} = \mathbf{a} + 2\mathbf{b}\) oe
A1: Also award A1 for an acceptable explanation in words.