22) B

Again, check if two colours will suffice. You will notice that this is not possible. Since there is an odd number of triangular faces on each pyramid, the fifth face cannot be of the same colour as the first or the fourth.
Check if three colours suffice. You will realise that this is correct.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s