CAIE S2 2020 June — Question 2

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2020
SessionJune
TopicLinear combinations of normal random variables
TypeComparison involving sums or multiples

2 Each day at the gym, Sarah completes three runs. The distances, in metres, that she completes in the three runs have the independent distributions \(W \sim \mathrm {~N} ( 1520,450 ) , X \sim \mathrm {~N} ( 2250,720 )\) and \(Y \sim \mathrm {~N} ( 3860,1050 )\). Find the probability that, on a particular day, \(Y\) is less than the total of \(W\) and \(X\).