This book is published as a companion to the Haese & Harris Publications Mathematics HL CORE textbook. It offers coverage of the Options set out in the Mathematics HL course (first examinations 2006). Details of the Topics and authors are as follows: •Topic 8 – Option: Statistics and probability (by Paul Urban, Prince Alfred College, Australia) •Topic 9 – Option: Sets, relations and groups (by David Martin, St Peter’s College, Australia) •Topic 10 – Option: Series and differential equations (by Peter Joseph, Ardingly College, UK) •Topic 11 – Option: Discrete mathematics (by Peter Blythe, United World College of SE Asia, Singapore) The accompanying CD includes many interactive features, and it also includes coverage of an additional Topic, for Further Mathematics students: Euclidean Geometry (by Peter Blythe, United World College of SE Asia, Singapore) Note: HL Options does not have a separate book of worked solutions – detailed solutions are given at the back of the textbook.