| Exam Board | WJEC |
|---|---|
| Module | Unit 3 (Unit 3) |
| Year | 2024 |
| Session | June |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Arithmetic Sequences and Series |
| Type | Sum of specific range of terms |
| Difficulty | Moderate -0.8 Part (a) is a straightforward arithmetic series summation using standard formulas (sum of r and sum of constants). Part (b) is a basic infinite geometric series with |r|<1, requiring only the formula S=a/(1-r). Both parts are routine applications of A-level formulas with minimal problem-solving, making this easier than average but not trivial due to the algebraic manipulation required. |
| Spec | 1.04g Sigma notation: for sums of series1.04h Arithmetic sequences: nth term and sum formulae1.04j Sum to infinity: convergent geometric series |r|<1 |
Showing all your working, evaluate
\begin{enumerate}[label=(\alph*)]
\item $\sum_{r=3}^{50} (4r + 5)$ [4]
\item $\sum_{r=2}^{\infty} \left(540 \times \left(\frac{1}{3}\right)^r\right)$. [3]
\end{enumerate}
\hfill \mbox{\textit{WJEC Unit 3 2024 Q7 [7]}}