ABCD is a rectangle; M, N are midpoints of AB, CD respectively. The circles touch the rectangle sides and each other. If AB=10 cm, what is the area of the grey region?
Ivor records a knockout tournament’s quarter-finals, semi-finals and final, in no particular order: Bart beat Antony, Carl beat Damien, Glen beat Henry, Glen beat Carl, Carl beat Bart, Ed beat Fred, Glen beat Ed. Who played the final?
Three equilateral triangles are cut from the corners of a larger equilateral triangle of perimeter 60 cm. The remaining figure F has perimeter 40 cm. What is the sum of the perimeters of the three removed triangles?
Tim, Tom, Jim are triplets, born on the same day. Their twin brothers John and James are 3 years younger. Which number could be the sum of the ages of all five?
A 3 cm-wide rectangular paper strip is green on one side and yellow on the other. Maria folds it as shown; the green trapeziums are identical. The folded strip spans 27 cm, and the first-fold detail marks a 6 cm vertical part. What is the original strip length?
Kangaroos Jum and Per start jumping simultaneously from the same point in the same direction, one jump per second. Every Jum jump is 6 m. Per’s jumps are 1 m,2 m,3 m, and so on. After how many jumps does Per catch Jum?
Twenty students sit in pairs. Exactly one third of the boys sit with a girl, and exactly one half of the girls sit with a boy. How many boys are there?