| Exam Board | Edexcel |
|---|---|
| Module | C2 (Core Mathematics 2) |
| Year | 2013 |
| Session | June |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Geometric Sequences and Series |
| Type | Find sum to infinity |
| Difficulty | Moderate -0.8 This is a straightforward geometric series question requiring only standard formula application: finding r from consecutive terms (r = 12/18 = 2/3), calculating the third term (p = 12 × 2/3 = 8), and applying the sum formula S_n = a(1-r^n)/(1-r). All steps are routine recall with no problem-solving or insight required, making it easier than average but not trivial since it involves multiple parts and calculator work. |
| Spec | 1.04e Sequences: nth term and recurrence relations1.04i Geometric sequences: nth term and finite series sum |
\begin{enumerate}
\item The first three terms of a geometric series are
\end{enumerate}
$$18,12 \text { and } p$$
respectively, where $p$ is a constant.
Find\\
(a) the value of the common ratio of the series,\\
(b) the value of $p$,\\
(c) the sum of the first 15 terms of the series, giving your answer to 3 decimal places.\\
\hfill \mbox{\textit{Edexcel C2 2013 Q1 [4]}}