题目
A bakery sells muffins individually at an average rate of 8 muffins per hour.
(a) Find the probability that, in a randomly selected one-hour period, the bakery sells at least 4 but not more than 8 muffins.
A sample of 5 non-overlapping half-hour periods is selected at random.
(b) Find the probability that the bakery sells fewer than 3 muffins in exactly 2 of these periods.
Given that 4 muffins were sold in a one-hour period, (c) find the probability that more muffins were sold in the first 15 minutes than in the last 45 minutes.
(Total for Question 7 is 12 marks)
题目中文翻译
一家面包店平均每小时单独售出 8 个松饼。
(a) 求在随机选取的一小时内，面包店售出至少 4 个但不超过 8 个松饼的概率。
随机选取 5 个互不重叠的半小时区间。
(b) 求在这 5 个时间段中，恰好有 2 个时间段里面包店售出少于 3 个松饼的概率。
已知在一小时内售出了 4 个松饼， (c) 求前 15 分钟售出的松饼数多于最后 45 分钟售出的概率。
（第 7 题共 12 分）