| Exam Board | OCR MEI |
|---|---|
| Module | Paper 2 (Paper 2) |
| Year | 2024 |
| Session | June |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Conditional Probability |
| Type | Basic two-way table probability |
| Difficulty | Easy -1.2 This is a straightforward conditional probability question using a two-way table. Part (a) requires basic arithmetic to complete the table, and part (b) is a direct application of the conditional probability formula P(A|B) = P(A∩B)/P(B) with values readily available from the completed table. No conceptual difficulty or problem-solving insight required—purely mechanical execution of standard techniques. |
| Spec | 2.03c Conditional probability: using diagrams/tables |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| Completed two-way table with entries: \(C\): 0.24, 0.12, 0.36; \(C'\): 0.18, 0.46, 0.64; totals: 0.42, 0.58, 1 | B1, B1 | Entries in bold; second B1 for 0.46 |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| \(\frac{\text{their } 0.46}{\text{their } 0.58}\) oe | M1 | Must use values from their table; \(0 <\) their \(0.46 <\) their \(0.58 < 1\) |
| \(\frac{23}{29}\) or \(0.79(31...)\) | A1FT |
## Question 5:
### Part (a):
| Answer | Marks | Guidance |
|--------|-------|----------|
| Completed two-way table with entries: $C$: 0.24, **0.12**, 0.36; $C'$: **0.18**, 0.46, **0.64**; totals: 0.42, **0.58**, 1 | B1, B1 | Entries in bold; second B1 for 0.46 |
### Part (b):
| Answer | Marks | Guidance |
|--------|-------|----------|
| $\frac{\text{their } 0.46}{\text{their } 0.58}$ oe | M1 | Must use values from their table; $0 <$ their $0.46 <$ their $0.58 < 1$ |
| $\frac{23}{29}$ or $0.79(31...)$ | A1FT | |
---\begin{enumerate}[label=(\alph*)]
\item In the Printed Answer Booklet, complete the copy of the two-way table.
\item Calculate the probability that an A-level student selected at random does not study chemistry given that they do not study mathematics.
\end{enumerate}
\hfill \mbox{\textit{OCR MEI Paper 2 2024 Q5 [4]}}