OCR MEI Paper 2 Specimen — Question 9

Exam BoardOCR MEI
ModulePaper 2 (Paper 2)
SessionSpecimen
TopicHypothesis test of Pearson’s product-moment correlation coefficient

9 A geyser is a hot spring which erupts from time to time. For two geysers, the duration of each eruption, \(x\) minutes, and the waiting time until the next eruption, \(y\) minutes, are recorded.
  1. For a random sample of 50 eruptions of the first geyser, the correlation coefficient between \(x\) and \(y\) is 0.758 .
    The critical value for a 2 -tailed hypothesis test for correlation at the \(5 \%\) level is 0.279 . Explain whether or not there is evidence of correlation in the population of eruptions. The scatter diagram in Fig. 9 shows the data from a random sample of 50 eruptions of the second geyser. \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{e9f3a5f3-210b-453d-9ff5-8518340f5689-07_794_1298_383_251} \captionsetup{labelformat=empty} \caption{Fig. 9}
    \end{figure}
  2. Stella claims the scatter diagram shows evidence of correlation between duration of eruption and waiting time. Make two comments about Stella's claim.