| Exam Board | Edexcel |
|---|---|
| Module | C1 (Core Mathematics 1) |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Topic | Arithmetic Sequences and Series |
| Type | Sigma notation: arithmetic series evaluation |
| Difficulty | Easy -1.2 This is a straightforward C1 arithmetic series question requiring only direct substitution and application of the standard sum formula. Parts (a) and (b) involve simple evaluation and subtraction, while part (c) is a routine application of S_n = n/2(a + l) or the summation formula. No problem-solving insight is needed—just mechanical execution of standard procedures. |
| Spec | 1.04h Arithmetic sequences: nth term and sum formulae |
The sum of an arithmetic series is
$$\sum_{r=1}^{n} (80 - 3r).$$
\begin{enumerate}[label=(\alph*)]
\item Write down the first two terms of the series. [2]
\item Find the common difference of the series. [1]
\end{enumerate}
Given that $n = 50$,
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{2}
\item find the sum of the series. [3]
\end{enumerate}
\hfill \mbox{\textit{Edexcel C1 Q29 [6]}}