CAIE S2 2018 June — Question 6

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2018
SessionJune
TopicLinear combinations of normal random variables
TypeComparing two journey times

6 The times, in minutes, taken to complete the two parts of a task are normally distributed with means 4.5 and 2.3 respectively and standard deviations 1.1 and 0.7 respectively.
  1. Find the probability that the total time taken for the task is less than 8.5 minutes.
  2. Find the probability that the time taken for the first part of the task is more than twice the time taken for the second part.