OCR MEI Paper 3 Specimen — Question 7 2 marks

Exam BoardOCR MEI
ModulePaper 3 (Paper 3)
SessionSpecimen
Marks2
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Mark schemeDownload PDF ↗
TopicProof
TypeCounter example to disprove statement
DifficultyModerate -0.8 This is a straightforward counter-example question testing understanding of reciprocals with negative numbers. Students simply need to recognize that choosing p = -2 and q = -1 (or any negative values with p < q) immediately disproves the statement, requiring minimal calculation and no extended reasoning.
Spec1.01c Disproof by counter example
7 By finding a counter example, disprove the following statement. If \(p\) and \(q\) are non-zero real numbers with \(p < q\), then \(\frac { 1 } { p } > \frac { 1 } { q }\).
Question 7:
AnswerMarks Guidance
AnswerMarks Guidance
E.g. \(p = -1,\ q = 2\)B1 3.1a
\(\frac{1}{p} = -1,\ \frac{1}{q} = \frac{1}{2}\)E1 2.1
So \(\frac{1}{p} < \frac{1}{q}\) for these values. 
## Question 7:

| Answer | Marks | Guidance |
|--------|-------|----------|
| E.g. $p = -1,\ q = 2$ | B1 | 3.1a | correct counter example stated |
| $\frac{1}{p} = -1,\ \frac{1}{q} = \frac{1}{2}$ | E1 | 2.1 | shown |
| So $\frac{1}{p} < \frac{1}{q}$ for these values. | | | **[2]** |

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7 By finding a counter example, disprove the following statement.

If $p$ and $q$ are non-zero real numbers with $p < q$, then $\frac { 1 } { p } > \frac { 1 } { q }$.

\hfill \mbox{\textit{OCR MEI Paper 3  Q7 [2]}}
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