In a row of five squares, each square is to be colored either red, yellow, or blue, so that no two consecutive squares have the same color, and at lest three of the squares are red. How many ways are there to color the five squares?
If 3 squares have to be red, then the first, third, and last have to be red, given that no two consecutive squares have the same color. So since there are only 2 other possible colors, there are 4 ways to color the other 2 squares: yellow then yellow, blue then blue, yellow then blue, and blue then yellow. Hope it helps :D!