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IAL 2023 June S2 Q6

A Level / Edexcel / S2

IAL 2023 June Paper · Question 6

题目

Problem

Akia selects at random a value from the continuous random variable WW, which is uniformly distributed over the interval [a,b][a, b]

The probability that Akia selects a value less than kk is 15\dfrac{1}{5} The probability that Akia selects a value greater than 17 is 5360\dfrac{53}{60}

(a) Find the probability that Akia selects a value between 17 and kk

(2)

It is known that Var(W)=75\operatorname{Var}(W) = 75

(b) (i) Find the value of aa and the value of bb

(ii) Find the value of kk

(4)

(c) Find P(5<W<5)P(-5 < W < 5)

(2)

(d) Find E(W2)E(W^2)

(2)

(Total for Question 6 is 12 marks)

题目中文翻译

Akia 随机从连续随机变量 WW 中选取一个值,WW 在区间 [a,b][a, b] 上均匀分布。

Akia 选到小于 kk 的值的概率为 15\dfrac{1}{5}。 Akia 选到大于 17 的值的概率为 5360\dfrac{53}{60}

(a) 求 Akia 选到介于 17 和 kk 之间的值的概率。

已知 Var(W)=75\operatorname{Var}(W) = 75

(b) (i) 求 aabb 的值。

(ii) 求 kk 的值。

(c) 求 P(5<W<5)P(-5 < W < 5)

(d) 求 E(W2)E(W^2)

(第 6 题共 12 分)

解答