| Exam Board | Edexcel |
|---|---|
| Module | S3 (Statistics 3) |
| Year | 2013 |
| Session | June |
| Marks | 10 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Chi-squared test of independence |
| Type | Standard 2×2 contingency table |
| Difficulty | Moderate -0.3 This is a standard chi-squared test of independence with a 2×2 contingency table requiring routine calculation of expected frequencies, test statistic, and comparison with critical value. While it requires multiple steps, it's a textbook application with no conceptual challenges beyond S3 syllabus expectations, making it slightly easier than average. |
| Spec | 5.06a Chi-squared: contingency tables |
| \backslashbox{Intake of saturated fats}{Cholesterol level} | High | Low |
| High | 12 | 8 |
| Low | 26 | 54 |
\begin{enumerate}
\item A doctor takes a random sample of 100 patients and measures their intake of saturated fats in their food and the level of cholesterol in their blood. The results are summarised in the table below.
\end{enumerate}
\begin{center}
\begin{tabular}{|l|l|l|}
\hline
\backslashbox{Intake of saturated fats}{Cholesterol level} & High & Low \\
\hline
High & 12 & 8 \\
\hline
Low & 26 & 54 \\
\hline
\end{tabular}
\end{center}
Using a $5 \%$ level of significance, test whether or not there is an association between cholesterol level and intake of saturated fats. State your hypotheses and show your working clearly.\\
\hfill \mbox{\textit{Edexcel S3 2013 Q1 [10]}}