95% of students at school weigh between 62 kg and 90 kg. Assuming this data is normally distributed, what are the mean and standard deviation?

QUESTION POSTED AT 18/04/2020 - 06:48 PM

Answered by admin AT 18/04/2020 - 06:48 PM

We can calculate (62 + 90) / 2 = 76. it's known that 95% lies between the mean and twice the standard deviation. if the mean is "μ" and the standard deviation is "σ": μ-2σ and μ+2σ. if μ=76, then 76+2σ = 90, so 2σ = 14, so σ = 7.

the mean is 76 and the standard deviation 7. 
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