CAPE Pure Mathematics Unit 2 · May/June 2015 · Paper 1 · Question Q20

Which of the following series are arithmetic series? \begin{align*} \text{I.} & \quad \sum_{r=1}^n (7 + 3r) \\ \text{II.} & \quad \sum_{r=1}^n 2(3^r) \\ \text{III.} & \quad \sum_{r=1}^n \log_{10}(r + 1) \\ \text{IV.} & \quad \sum_{r=1}^n \log_{10} 3^{(r+1)} \end{align*}

1. (A)I and III only
2. (B)I and IV only
3. (C)III and IV only
4. (D)I, II and IV only