7 The length of time a person undergoing a routine operation stays in hospital can be modelled by a normal distribution with mean 7.8 days and standard deviation 2.8 days.
- Calculate the proportion of people who spend between 7.8 days and 11.0 days in hospital.
- Calculate the probability that, of 3 people selected at random, exactly 2 spend longer than 11.0 days in hospital.
- A health worker plotted a box-and-whisker plot of the times that 100 patients, chosen randomly, stayed in hospital. The result is shown below.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{26776153-9477-4155-b5e4-f35e6d33a5ff-3_447_917_767_657}
\captionsetup{labelformat=empty}
\caption{Days}
\end{figure}
State with a reason whether or not this agrees with the model used in parts (i) and (ii).