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3.5 Finding the mean and standard deviation

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Question 38

The random variable $X$ is normally distributed with mean $μ\mu$ and variance $25$ . Given that $P(μ−3k<X<μ+3k)=0.7P(\mu - 3k < X < \mu + 3k) = 0.7$ :

find the value of $k$ .

[3]

The random variable $Y$ is normally distributed with mean $μ\mu$ and standard deviation $σ\sigma$ . Given that $3μ=4σ23\mu = 4\sigma^2$ and $P(Y>54μ)=0.0228P\left(Y > \frac{5}{4}\mu\right) = 0.0228$ : find the value of $μ\mu$ and the value of $σ\sigma$ .

[5]

Markscheme

3.5 Finding the mean and standard deviation Questions

A Level
Maths
3.5 Finding the mean and standard deviation

48 exam-style questions on Edexcel A Level Maths 3.5 Finding the mean and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.

3.5 Finding the mean and standard deviation

Question bank

3.5 Finding the mean and standard deviation

Medium Hard

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Question 38

The random variable $X$ is normally distributed with mean $μ\mu$ and variance $25$ . Given that $P(μ−3k<X<μ+3k)=0.7P(\mu - 3k < X < \mu + 3k) = 0.7$ :

find the value of $k$ .

[3]

[5]

Markscheme

3.5 Finding the mean and standard deviation Questions

A Level
Maths
3.5 Finding the mean and standard deviation

48 exam-style questions on Edexcel A Level Maths 3.5 Finding the mean and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.