求助！11年4月回忆题有一道想不通

frank2363UID: 2199951

7，a dodecagon labelled by 12 months at each edge is rolled in a game. One “turn” of the game is to roll it until one April appears, then the number of the rolls is recorded. What is the probability to have five consecutive turns with rolls no greater than 10?

这题答案有人说是 (1-(11/12)^10)^5，为什么呢？

frank2363UID: 2199951

明白了，谢谢！

ryanzhoupkuUID: 2846827

1# frank2363
11/12：投一次不是april
(11/12)^10：前十次都不是april，亦即投的次数大于10
(1-(11/12)^10)：一局中投的次数<=10
(1-(11/12)^10)^5：连续5局投的次数<=10