| Exam Board | Edexcel |
|---|---|
| Module | S2 (Statistics 2) |
| Year | 2003 |
| Session | January |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | 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. Part (a) tests basic understanding that rounding errors follow U(-0.5, 0.5), part (b) is a simple probability calculation (0.4/1 = 0.4), and part (c) applies independence by squaring. The question requires only recall of the standard measurement error model and basic probability calculations, making it easier than average for A-level. |
| Spec | 5.03a Continuous random variables: pdf and cdf |
\begin{enumerate}
\item An engineer measures, to the nearest cm , the lengths of metal rods.\\
(a) Suggest a suitable model to represent the difference between the true lengths and the measured lengths.\\
(b) Find the probability that for a randomly chosen rod the measured length will be within 0.2 cm of the true length.
\end{enumerate}
Two rods are chosen at random.\\
(c) Find the probability that for both rods the measured lengths will be within 0.2 cm of their true lengths.\\
\hfill \mbox{\textit{Edexcel S2 2003 Q1 [6]}}