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IAL 2024 June S3 Q7

A Level / Edexcel / S3

IAL 2024 June Paper · Question 7

题目

Problem

The continuous random variable D is uniformly distributed over the interval [x – 1, x + 5] where x is a constant.

A random sample of n observations of D is taken, where n is large.

(a) Use the Central Limit Theorem to find an approximate distribution for Dˉ\bar D Give your answer in terms of n and x where appropriate.

The n observations of D have a sample mean of 24.6 Given that the lower bound of the 99% confidence interval for x is 22.101 to 3 decimal places,

(b) find the value of n Show your working clearly.

(3)
(5)
(Total for Question 7 is 8 marks)
题目中文翻译

连续随机变量 D 在区间 [x – 1, x + 5] 上均匀分布,其中 x 为常数。

从 D 中抽取 n 个观测值的随机样本,且 n 很大。

(a) 利用中心极限定理求 Dˉ\bar D 的近似分布。 如适用,请用 n 和 x 表示你的答案。

这 n 个 D 的观测值的样本平均数为 24.6。 已知 x 的 99% 置信区间下限为 22.101, 保留到 3 位小数,

(b) 求 n 的值。 请清楚写出你的过程。

解答