现有一游戏装置如图,小球从最上方入口处投入,每次遇到黑色障碍物,等可能地向左,右两边落下.游戏规则为:若小球最终落入A槽,得10张奖票;若落入B槽,得5张奖票;若落入C槽,得重投一次的机会,但投球的总次数不超过3次.
(1)求投球一次,小球落入B槽的概率;
(2)设玩一次游戏能获得的奖票数为随机变量ξ,并求ξ的分布列及数学期望.
考点分析:
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