Vivek is painting three doors. The doors are numbered 1, 2 and 3.
Each door is to be painted one colour: either black or gold. One
possibility is that door 1 is painted black, door 2 is painted gold, and
door 3 is painted gold. In total, how many different ways can the three
doors be painted?
, 2023
Pick one
Solution
Since there are 3 doors and 2 colour choices for each door, there
are ways of painting the
three doors.
Using “B” to represent black and “G” to represent gold, these ways are
BBB, BBG, BGB, BGG, GBB, GBG, GGB, and GGG.
Want a route through all this instead of an archive? The track
puts 2,444 problems in a working order, from Junior Challenge level to the IMO shortlist.