| Exam Board | AQA |
|---|---|
| Module | AS Paper 2 (AS Paper 2) |
| Year | 2018 |
| Session | June |
| Marks | 1 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Discrete Probability Distributions |
| Type | One unknown from sum constraint only |
| Difficulty | Easy -1.8 This is a trivial probability distribution question requiring only the knowledge that probabilities sum to 1, followed by basic arithmetic (0.35 + 0.25 + 0.14 + 0.1 = 0.84, so k = 0.16). It's a 1-mark multiple choice question testing fundamental recall with no problem-solving element. |
| Spec | 2.04a Discrete probability distributions |
| \(x\) | 0 | 1 | 2 | 3 | 4 or more |
| P(X = x) | 0.35 | 0.25 | \(k\) | 0.14 | 0.1 |
| Answer | Marks | Guidance |
|---|---|---|
| 13 | Circles correct answer | AO1.1b |
| Total | 1 | |
| Q | Marking Instructions | AO |
Question 13:
13 | Circles correct answer | AO1.1b | B1 | 0.16
Total | 1
Q | Marking Instructions | AO | Marks | Typical SolutionThe table below shows the probability distribution for a discrete random variable $X$.
\begin{tabular}{|c|c|c|c|c|c|}
\hline
$x$ & 0 & 1 & 2 & 3 & 4 or more \\
\hline
P(X = x) & 0.35 & 0.25 & $k$ & 0.14 & 0.1 \\
\hline
\end{tabular}
Find the value of $k$.
Circle your answer.
0.14 \quad 0.16 \quad 0.18 \quad 1
[1 mark]
\hfill \mbox{\textit{AQA AS Paper 2 2018 Q13 [1]}}