| Exam Board | OCR |
|---|---|
| Module | C2 (Core Mathematics 2) |
| Year | 2009 |
| Session | January |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Arithmetic Sequences and Series |
| Type | Sequence defined by formula |
| Difficulty | Moderate -0.8 This is a straightforward C2 question requiring direct substitution into a formula, solving a simple linear equation, and applying the standard arithmetic series sum formula. All three parts are routine calculations with no problem-solving or conceptual challenges beyond basic recall. |
| Spec | 1.04e Sequences: nth term and recurrence relations1.04g Sigma notation: for sums of series1.04h Arithmetic sequences: nth term and sum formulae |
3 A sequence of terms $u _ { 1 } , u _ { 2 } , u _ { 3 } , \ldots$ is defined by
$$u _ { n } = 24 - \frac { 2 } { 3 } n$$
(i) Write down the exact values of $u _ { 1 } , u _ { 2 }$ and $u _ { 3 }$.\\
(ii) Find the value of $k$ such that $u _ { k } = 0$.\\
(iii) Find $\sum _ { n = 1 } ^ { 20 } u _ { n }$.
\hfill \mbox{\textit{OCR C2 2009 Q3 [7]}}