| Exam Board | Edexcel |
|---|---|
| Module | C2 (Core Mathematics 2) |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Topic | Geometric Sequences and Series |
| Type | Find common ratio from terms |
| Difficulty | Moderate -0.3 This is a straightforward geometric series question requiring standard formula manipulation. Students must use ar³=10 and ar⁶=80 to find r=2, then back-substitute for a=1.25, and finally apply the sum formula. While it involves multiple steps (6 marks total), each step follows directly from standard GP formulas with no conceptual difficulty or novel insight required, making it slightly easier than average. |
| Spec | 1.04i Geometric sequences: nth term and finite series sum |
The fourth term of a geometric series is 10 and the seventh term of the series is 80.
For this series, find
\begin{enumerate}[label=(\alph*)]
\item the common ratio,
[2]
\item the first term,
[2]
\item the sum of the first 20 terms, giving your answer to the nearest whole number.
[2]
\end{enumerate}
\hfill \mbox{\textit{Edexcel C2 Q2 [6]}}