CAIE S1 2009 November — Question 3

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2009
SessionNovember
TopicNormal Distribution
TypeMixed calculations with boundaries

3 The times for a certain car journey have a normal distribution with mean 100 minutes and standard deviation 7 minutes. Journey times are classified as follows: \begin{displayquote} 'short' (the shortest \(33 \%\) of times),
'long' (the longest \(33 \%\) of times),
'standard' (the remaining 34\% of times).
  1. Find the probability that a randomly chosen car journey takes between 85 and 100 minutes.
  2. Find the least and greatest times for 'standard' journeys. \end{displayquote}