| Exam Board | OCR MEI |
|---|---|
| Module | C2 (Core Mathematics 2) |
| Marks | 5 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Arithmetic Sequences and Series |
| Type | Sigma notation: direct numerical evaluation |
| Difficulty | Moderate -0.8 Part (i) is straightforward summation of five terms by substitution. Part (ii) involves recognizing an arithmetic sequence and applying standard formulas for the nth term and sum, requiring only direct application of memorized formulas with minimal algebraic manipulation. |
| Spec | 1.04g Sigma notation: for sums of series1.04h Arithmetic sequences: nth term and sum formulae |
| Answer | Marks | Guidance |
|---|---|---|
| 3 | (i) | 1 1 1 1 1 |
| Answer | Marks |
|---|---|
| 20 20 | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| [2] | may be implied by correct answer | NB 7 + 5.25 + 4.2 + 3.5 + 3 |
| Answer | Marks | Guidance |
|---|---|---|
| 3 | (ii) | a + 45 cao |
| Answer | Marks |
|---|---|
| 5(2a + 45)or 10a+ 225 cao isw | B1 |
| Answer | Marks |
|---|---|
| [3] | mark the final answer |
| Answer | Marks |
|---|---|
| ignore further work attempting to find a | condone wrongly attributed |
Question 3:
3 | (i) | 1 1 1 1 1
21 oe
1 2 2 2 3 2 4 2 5 2
soi
459 19
22.95 or or 22
20 20 | M1
A1
[2] | may be implied by correct answer | NB 7 + 5.25 + 4.2 + 3.5 + 3
M0 if extra terms or terms missing
3 | (ii) | a + 45 cao
10
a a their45
2
5(2a + 45)or 10a+ 225 cao isw | B1
M1
A1
[3] | mark the final answer
must be explicitly stated
10
or 2a (10 1) 5
2
ignore further work attempting to find a | condone wrongly attributed
answers
B2 if correct answer derived from
adding terms separately\begin{enumerate}[label=(\roman*)]
\item Find $\sum_{r=1}^{5} \frac{21}{r+2}$. [2]
\item A sequence is defined by
$$u_1 = a, \text{ where } a \text{ is an unknown constant,}$$
$$u_{n+1} = u_n + 5.$$
Find, in terms of $a$, the tenth term and the sum of the first ten terms of this sequence. [3]
\end{enumerate}
\hfill \mbox{\textit{OCR MEI C2 Q3 [5]}}