1. In how many ways can 4 red balls, 3 white balls and 1 black ball be arranged in a line so that the black ball is always surrounded by a red and a white ball?
2. In how many ways can the balls be arranged if no red ball is next to a white?
Thank you in advanced.
2. In how many ways can the balls be arranged if no red ball is next to a white?
Thank you in advanced.