OCR MEI C2 — Question 3 5 marks

Exam BoardOCR MEI
ModuleC2 (Core Mathematics 2)
Marks5
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Mark schemeDownload PDF ↗
TopicArithmetic Sequences and Series
TypeFind term or common difference
DifficultyModerate -0.3 This is a straightforward two-equation system using standard AP formulas (a + 10d = 1 and Sā‚ā‚€ = 120). It requires routine algebraic manipulation with no conceptual challenges, making it slightly easier than average but still requiring proper method application.
Spec1.04h Arithmetic sequences: nth term and sum formulae
3 The 11th term of an arithmetic progression is 1. The sum of the first 10 terms is 120. Find the 4th term.
Question 3:
AnswerMarks
M1\(a + 10d = 1\) or \(121 = 5.5(2a+10d)\)
M1\(5(2a + 9d) = 120\) o.e. or \(2a + 9d = 24\)
A1\(a = 21\) s.o.i. www
A1\(d = -2\) s.o.i. www
A14th term is 15
Note: \(121 = 5.5(a + 1)\) gets M2
Question 3:

M1 | $a + 10d = 1$ or $121 = 5.5(2a+10d)$

M1 | $5(2a + 9d) = 120$ o.e. or $2a + 9d = 24$

A1 | $a = 21$ s.o.i. www

A1 | $d = -2$ s.o.i. www

A1 | 4th term is 15

Note: $121 = 5.5(a + 1)$ gets M2
3 The 11th term of an arithmetic progression is 1. The sum of the first 10 terms is 120. Find the 4th term.

\hfill \mbox{\textit{OCR MEI C2  Q3 [5]}}
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Q1 12 Q2 3 Q3 5 Q4 12 Q5 3