Question 25
Peter colours a 4-by-4 square grid so that each row, each column and each diagonal contains four different colours. What is the smallest number of colours needed?
Original printed choices: A) 4; B) 5; C) 6; D) 7; E) 8
Editorial note: Explain whether the printed question and choices are consistent. Give the literal mathematical result and distinguish any intended correction.
Original printed choices: A) 4; B) 5; C) 6; D) 7; E) 8
Editorial note: Explain whether the printed question and choices are consistent. Give the literal mathematical result and distinguish any intended correction.