| Exam Board | Edexcel |
|---|---|
| Module | S4 (Statistics 4) |
| Year | 2005 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | F-test and chi-squared for variance |
| Type | F-test two variances hypothesis |
| Difficulty | Standard +0.3 This is a straightforward F-test for equality of variances with clearly stated hypotheses, standard procedure, and small sample sizes. The calculation is routine (F = 14²/8² = 3.0625, compare to critical value), but it's slightly above average difficulty because F-tests are less commonly encountered than t-tests and require understanding of the F-distribution with two degrees of freedom parameters. |
| Spec | 5.05c Hypothesis test: normal distribution for population mean |
2. The standard deviation of the length of a random sample of 8 fence posts produced by a timber yard was 8 mm . A second timber yard produced a random sample of 13 fence posts with a standard deviation of 14 mm .
\begin{enumerate}[label=(\alph*)]
\item Test, at the $10 \%$ significance level, whether or not there is evidence that the lengths of fence posts produced by these timber yards differ in variability. State your hypotheses clearly.
\item State an assumption you have made in order to carry out the test in part (a).
\end{enumerate}
\hfill \mbox{\textit{Edexcel S4 2005 Q2 [6]}}