The lifetime of Lumos LED bulbs, XXX units of hours, is normally distributed with mean 12,000 hours and standard deviation 800 hours.
Find P(X≠12000)P(X \neq 12000)P(X=12000).
Find P(11000<X<13500)P(11000 < X < 13500)P(11000<X<13500).
Determine the lifetime exceeded by 80% of Lumos LED bulbs.
A different brand, Glow, has its bulb lifetime, YYY hours, modelled by a normal distribution with mean 11,000 hours and standard deviation σ\sigmaσ. Given that 15% of randomly selected Glow bulbs last less than 9,500 hours, find the value of σ\sigmaσ, correct to three significant figures.
Practise Edexcel A Level Maths The Normal Distribution with exam-style questions for A Level Maths. 439 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.
