The random variable XXX is normally distributed with mean μ\muμ and variance 252525. Given that P(μ−3k<X<μ+3k)=0.7P(\mu - 3k < X < \mu + 3k) = 0.7P(μ−3k<X<μ+3k)=0.7:
find the value of kkk.
The random variable YYY is normally distributed with mean μ\muμ and standard deviation σ\sigmaσ. Given that 3μ=4σ23\mu = 4\sigma^23μ=4σ2 and P(Y>54μ)=0.0228P\left(Y > \frac{5}{4}\mu\right) = 0.0228P(Y>45μ)=0.0228: find the value of μ\muμ and the value of σ\sigmaσ.
Practise Edexcel A Level Maths Finding the mean and standard deviation with exam-style questions for A Level Maths. 48 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
