2只宠物合成,1只有5技能,1只有4技能,每个技能有 a%概率遗传,请问刚好有7 个技能遗传成功的概率是?
- (a%)^7*(C(5,5)*C(4,2) + C(5,2)*C(4,3) + C(5,2)*C(4,4))
- (a%)^7*(C(5,4)*C(4,3) + C(5,3)*C(4,4) + C(5,3)*C(4,4))
- (a%)^7*(C(5,5)*C(4,2) + C(5,4)*C(4,3) + C(5,3)*C(4,4))
- (a%)^7*(C(5,2)*C(4,4) + C(5,3)*C(4,4) + C(5,4)*C(4,3))