CAIE S2 2018 November — Question 5

Exam BoardCAIE
ModuleS2 (Statistics 2)
Year2018
SessionNovember
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TopicLinear combinations of normal random variables

5 The times, in months, taken by a builder to build two types of house, \(P\) and \(Q\), are represented by the independent variables \(T _ { 1 } \sim \mathrm {~N} \left( 2.2,0.4 ^ { 2 } \right)\) and \(T _ { 2 } \sim \mathrm {~N} \left( 2.8,0.5 ^ { 2 } \right)\) respectively.
  1. Find the probability that the total time taken to build one house of each type is less than 6 months.
  2. Find the probability that the time taken to build a type \(Q\) house is more than 1.2 times the time taken to build a type \(P\) house.

5 The times, in months, taken by a builder to build two types of house, $P$ and $Q$, are represented by the independent variables $T _ { 1 } \sim \mathrm {~N} \left( 2.2,0.4 ^ { 2 } \right)$ and $T _ { 2 } \sim \mathrm {~N} \left( 2.8,0.5 ^ { 2 } \right)$ respectively.\\
(i) Find the probability that the total time taken to build one house of each type is less than 6 months.\\

(ii) Find the probability that the time taken to build a type $Q$ house is more than 1.2 times the time taken to build a type $P$ house.\\

\hfill \mbox{\textit{CAIE S2 2018 Q5}}