Edexcel S2 2023 October — Question 3

Exam BoardEdexcel
ModuleS2 (Statistics 2)
Year2023
SessionOctober
TopicContinuous Uniform Random Variables
TypeWaiting time applications

  1. Every morning Navtej travels from home to work. Navtej leaves home at a random time between 08:00 and 08:15
  • It always takes Navtej 3 minutes to walk to the bus stop
  • Buses run every 15 minutes and Navtej catches the first bus that arrives
  • Once Navtej has caught the bus it always takes a further 29 minutes for Navtej to reach work
The total time, \(T\) minutes, for Navtej's journey from home to work is modelled by a continuous uniform distribution over the interval \([ \alpha , \beta ]\)
    1. Show that \(\alpha = 32\)
    2. Show that \(\beta = 47\)
  1. State fully the probability density function for this distribution.
  2. Find the value of
    1. \(\mathrm { E } ( T )\)
    2. \(\operatorname { Var } ( T )\)
  3. Find the probability that the time for Navtej's journey is within 5 minutes of 35 minutes.