| Exam Board | Edexcel |
|---|---|
| Module | S4 (Statistics 4) |
| Year | 2008 |
| Session | June |
| Marks | 9 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Confidence intervals |
| Type | CI from raw data list |
| Difficulty | Standard +0.3 This is a straightforward confidence interval question requiring calculation of a t-interval from given summary statistics, stating the normality assumption, and making a simple interpretation. While it involves multiple parts, each step is routine for S4 students with no novel problem-solving required, making it slightly easier than average. |
| Spec | 5.05d Confidence intervals: using normal distribution |
4. A town council is concerned that the mean price of renting two bedroom flats in the town has exceeded $\pounds 650$ per month. A random sample of eight two bedroom flats gave the following results, $\pounds x$, per month.
$$705 , \quad 640 , \quad 560 , \quad 680 , \quad 800 , \quad 620 , \quad 580 , \quad 760$$
[You may assume $\sum x = 5345 \quad \sum x ^ { 2 } = 3621025$ ]
\begin{enumerate}[label=(\alph*)]
\item Find a 90\% confidence interval for the mean price of renting a two bedroom flat.
\item State an assumption that is required for the validity of your interval in part (a).
\item Comment on whether or not the town council is justified in being concerned. Give a reason for your answer.
\end{enumerate}
\hfill \mbox{\textit{Edexcel S4 2008 Q4 [9]}}