AAA格式概率 C(7,1)/7^3=1/49
AAB格式概率 C(7,1)*C(6,1)/7^3=6/49
ABB格式概率 C(7,1)*C(6,1)/7^3=6/49
ABA格式概率 C(7,1)*C(6,1)/7^3=6/49
另外:
ABC格式概率 P(7,3)/7^3=30/49
AAA格式概率 C(7,1)/7^3=1/49
AAB格式概率 C(7,1)*C(6,1)/7^3=6/49
ABB格式概率 C(7,1)*C(6,1)/7^3=6/49
ABA格式概率 C(7,1)*C(6,1)/7^3=6/49
另外:
ABC格式概率 P(7,3)/7^3=30/49