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. How many ways are there to color the five squares, if there
must be at least three yellow squares?
In order not to have two yellows next to each other,
the three yellows must occupy squares 1, 3, and 5.
That leaves squares 2 and 4 to fill, and two colors
to do it with. There are only four ways.
Blue Blue Red Red Blue Red Red Blue
So, the answer is four ways.
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