| Exam Board | Edexcel |
|---|---|
| Module | S2 (Statistics 2) |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Topic | Continuous Uniform Random Variables |
| Type | Measurement error modeling |
| Difficulty | Moderate -0.8 This is a straightforward application of the continuous uniform distribution with minimal problem-solving required. Students need to recognize the standard rounding error model U(-0.5, 0.5), calculate a simple probability as a ratio of intervals (0.4/1.0), and square it for independence. All steps are routine S2 techniques with no conceptual challenges or novel insights needed. |
| Spec | 5.02e Discrete uniform distribution |
An engineer measures, to the nearest cm, the lengths of metal rods.
\begin{enumerate}[label=(\alph*)]
\item Suggest a suitable model to represent the difference between the true lengths and the measured lengths. [2]
\item Find the probability that for a randomly chosen rod the measured length will be within 0.2 cm of the true length. [2]
\end{enumerate}
Two rods are chosen at random.
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{2}
\item Find the probability that for both rods the measured lengths will be within 0.2 cm of their true lengths. [2]
\end{enumerate}
\hfill \mbox{\textit{Edexcel S2 Q1 [6]}}