Professor Stewart’s Hoard of Mathematical Treasures
“You’re falling behind on your deliveries, Santa,” said his marketing consultant. “Well, Rudolph’s not got the energy he used to have—” “— and neither have you. Face it, you’re getting old. You need some help.” “But traditionally—” “This is the 21st century, Mr Claus. Efficiency is more important than some old tradition.” So Santa reorganised his delivery service, and as well as his original sleigh he now sends out four extra sleighs, each with an elf in charge. The elves are named Red, Yellow, Blue, and Green. Each wears a coloured hat. The colours available are red, yellow, blue, and green, and each colour is worn by exactly one elf. No elf wears a hat whose colour is the same as his name. Red does not wear a hat whose colour is the name of an elf that wears a red hat. The elf whose name is the colour of Green’s hat wears a hat whose colour is the name of the elf wearing a red hat. elf whose name is the colour of Yellow’s hat wears a hat whose colour is the name of the elf wearing a green hat. Which elf wears the blue hat? Answer next week.