The lifetime of a certain type of battery is normally distributed with a mean of 60 hours. Given that 8% of the batteries last less than 48 hours, find the standard deviation of the lifetimes.
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Markscheme
3.5 Finding the mean and standard deviation Questions
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.