Question

Nine tokens are black on one side and white on the other. Initially, four tokens have the black side up (see the picture). In each turn you have to flip three tokens. What is the least number of turns you need to have all tokens showing the same color?

Answer 1

2 Movements

Explanation:

Let us name the tokens

B-For Black Tokens

W-For White Tokens

The initial arrangement is therefore given as:

B-B-B-B-W-W-W-W-W

Since we are allowed to flip three tiles in each turn

First movement: Flip two blacks and one white, we would have:

B-B-W-W-W-W-W-W-B

Second movement: Flip the three black tokens, this would give us:

W-W-W-W-W-W-W-W-W

Therefore, the least number of movements to have all tokens showing the same color is 2.