Edexcel S1 2013 January — Question 4

Exam BoardEdexcel
ModuleS1 (Statistics 1)
Year2013
SessionJanuary
TopicNormal Distribution
TypeConditional probability with normal

  1. The length of time, \(L\) hours, that a phone will work before it needs charging is normally distributed with a mean of 100 hours and a standard deviation of 15 hours.
    1. Find \(\mathrm { P } ( L > 127 )\).
    2. Find the value of \(d\) such that \(\mathrm { P } ( L < d ) = 0.10\)
    Alice is about to go on a 6 hour journey.
    Given that it is 127 hours since Alice last charged her phone,
  2. find the probability that her phone will not need charging before her journey is completed.