You’ll have to sit the MAT (Mathematics Admissions Test) if you’re applying for Mathematics, Computer Science or related degrees at Oxford University and it is also used by Imperial College, London and the University of Warwick as part of their admissions procedure. You sit the MAT at the end of October/start of November in your school, and if you do well enough you will be invited for an interview in Oxford in December. More information and links to past papers with solutions can be found at the official website on the Mathematical Institute website of the University of Oxford.
I sat a paper very similar to this when I was accepted to Oxford to study Maths (then you sat it at interview in December though!) and I have helped a lot of students prepare for this paper too. I really wanted to share this advice more widely and have made video solutions to all of the 2018 paper and a lot of the 2016 and 2017 papers below, going through the answers but also good strategies and approaches to these papers.
2018 YouTube Playlist – MAT 2018 all questions 

2017  
YouTube Playlist – MAT 2017 – Short Answer A to J 

2016 YouTube Playlist – MAT 2016 – Short Answers and Q2 and 3 
