OCR S3 2011 January — Question 2

Exam BoardOCR
ModuleS3 (Statistics 3)
Year2011
SessionJanuary
TopicLinear combinations of normal random variables
TypeDifferent variables, one observation each

2 In a Year 8 internal examination in a large school the Geography marks, \(G\), and Mathematics marks, \(M\), had means and standard deviations as follows.
MeanStandard deviation
\(G\)36.426.87
\(M\)42.6510.25
Assuming that \(G\) and \(M\) have independent normal distributions, find the probability that a randomly chosen Geography candidate scores at least 10 marks more than a randomly chosen Mathematics candidate. Do not use a continuity correction.