I recently went to see the film x+y, which is really about autism, but centred on an autistic teenager who enters the Mathematical Olympiad, an international competition for high school students.

# Monthly Archives: March 2015

# S2 test paper, 26-27 March 2015

# D1 test paper, 26-27 March 2015

# M2 test paper, 26-27 March 2015

# D1: collections of questions from past papers, by topic and by date

**By topic**:

- Chinese postman
- Critical path analysis, Gantt charts, scheduling
- Dijkstra
- Kruskal and Prim
- Linear programming
- Matchings
- Sorting and binary search

**By date**

- D1 papers and answer books 2014-2013 (I recommend that as you do each paper, you neatly tear out the question paper so that you can have question paper and answer book separate in front of you)
- Mark schemes for those 2014-2013 papers
- D1 papers and answer books 2012-2010 (I recommend that as you do each paper, you neatly tear out the question paper so that you can have question paper and answer book separate in front of you)
- Mark schemes for those 2012-2010 papers

# S2 statistics past papers, by topic and by date, and other materials

**Collections of past-paper questions by topic**

- Sampling and hypothesis testing
- Continuous random variables
- Distributions: binomial, Poisson, normal, uniform

**Collections of full past papers by date**

- S2 papers 2014 to 2010
- S2 papers 2009 to 2007
- Mark scheme for June 2014 paper
- Mark scheme for June 2014 (R) paper

Mark schemes for other S2 past papers can be found at the Physics and Maths tutor website

# Why is the rule as it is for inverting 2×2 matrices?

The inverse of the 2×2 matrix

a b

c d

is

d −b

−c a

divided by the determinant, ad−bc Continue reading