在超市的抽奖活动中,参与者将首先转动转盘,然后掷一枚均匀的六面骰子。 转盘有 9 个区域和一根指针,指针停在 9 个区域中任意一个区域的概率均等。转盘上有一个区域标有 “4”,五个区域标有 “”。 均匀的六面骰子有两个面标有 “0.02”,三个面标有 “0.5”,一个面标有 “2”。 参与者赢得的奖金金额是通过将转盘和骰子的结果相乘来计算的。
- (a)
求参与者赢得 $2 的概率。
- (b)
如果一个参与者赢得了 100” 区域的概率。
- (c)
一个参与者连续进行三次抽奖。求该参与者总共赢得 $6,且每次骰子显示的数值都不同的概率。
- (d)
另一个参与者进行了一次抽奖。他现在可以选择通过拿走转盘所指区域对应的金额来结束游戏,或者继续掷骰子。解释并说明理由,他应该选择哪种方案。
它不会直接告诉你答案,而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的
完整解法
7(a)
1. Identify all the combinations of wheel and die outcomes that result in a $2 win.
The possible (wheel, die) combinations that multiply to $2 are:
- since
- since
- since
2. Calculate the probability for each combination and sum them to find the total probability.
7(b)
1. Retrieve or calculate the total probability of winning $2 from part (a).
From part (a), the probability of winning $2 is the sum of probabilities of the mutually exclusive winning combinations:
2. Calculate the probability that the participant lands on $100 AND wins $2.
The only way to win $2 when the wheel lands on $100 is for the die to show 0.02.
3. Apply the conditional probability formula to find the required probability.
Using the concept of conditional probability:
7(c)
1. Deduce the exact sequence of winnings required to win $6 with three different die face values.
Let the three different die face values rolled be , , and .
Let the corresponding wheel values landed on be .
Total winnings
Since , if , the total will exceed . Thus, we must have .
This leaves .
If , the sum exceeds . If , we get (impossible since the maximum wheel value is ).
Thus, must be , giving . This implies .
Therefore, the only way to satisfy the conditions is to win exactly in each of the three draws via these specific combinations:
- Wheel and Die
- Wheel and Die
- Wheel and Die
2. Calculate the total probability by considering the permutations of the three specific events.
Calculate the probability of each specific combination occurring in a single draw:
Since the participant plays three consecutive draws, these 3 distinct events can occur in any order. The number of possible arrangements is .
7(d)
1. Calculate the expected value (average) of the multiplier from throwing the die.
2. Compare the expected multiplier with 1 to justify the decision.
Since the expected multiplier is less than , throwing the die will, on average, decrease the final prize money regardless of what section the wheel came to rest over.
Therefore, he should choose to end the game and take the amount based on the wheel.
He should choose to end the game, as the expected multiplier from throwing the die is (which is less than ). Thus, throwing the die will decrease his expected prize.
AI 分析,可能出错
用 AI 批改,圈出写错的那一步,并自动将你的薄弱点存入错题本,形成你的错因库。
同一知识点的其他题
- 1一位业余作曲家正在编排一段由四个音符和接下来的三个节拍组成的序列。有 7 种可能的音符(标记为 A 到 G)和 5 种可能的节拍(标记为 1 到 5)。音符和节拍的顺序在创作中很重要。求随机选择的序列满足以下条件的概率: 第三个节拍的数字大…
- 2凯(Kai)和里奥(Leo)两兄弟是定期训练的双项全能(跑步和骑行)运动员。在每一天中,凯骑行的概率为 ,跑步的概率为 ,两者都进行的概率为 。 平均而言,里奥在一周的 7 天中有…
- 3色觉障碍(色盲)是指辨别颜色差异的能力降低。色觉正常的人能够将 6 种颜色(红、橙、黄、绿、蓝、紫)看作 6 个色带。 患有色觉障碍的 Deutan 无法区分以下两对颜色: (I) 红色和绿色, (II) 蓝色和紫色。 对于特定深浅的这 6…
- 4一对同胞 Abbey 和 Betty 还有其他六个朋友一起去参加书展。他们八个人随机排成一队等候一位著名作家的签名。求满足以下条件的概率: Abbey 排在队列第一位且 Betty 排在队列第六位, Abbey 排在队列第一位或 Betty…
- 5已知某种特定疾病的感染率约为万分之一(每 10 000 人中约有 1 人感染)。针对该疾病的一项检测准确率为 99.9%,即检测结果与真实情况相符的概率为 99.9%。求在已知某人检测结果呈阳性的条件下,此人确实患有该疾病的概率。 研究人员…