OCR MEI Paper 2 2019 June — Question 15

Exam BoardOCR MEI
ModulePaper 2 (Paper 2)
Year2019
SessionJune
TopicNormal Distribution
TypeSymmetric properties of normal

15 You must show detailed reasoning in this question. The screenshot in Fig. 15 shows the probability distribution for the continuous random variable \(X\), where \(X \sim \mathrm {~N} \left( \mu , \sigma ^ { 2 } \right)\). \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{95eb3bcc-6d3c-4f7e-9b27-5e046ab57ec5-11_387_954_1599_260} \captionsetup{labelformat=empty} \caption{Fig. 15}
\end{figure} The distribution is symmetrical about the line \(x = 35\) and there is a point of inflection at \(x = 31\).
Fifty independent readings of \(X\) are made. Show that the probability that at least 45 of these readings are between 30 and 40 is less than 0.05 .