The life of a cellphone battery has a lognormal distribution with μ = 4.5 and o= 0.4 (the mean and standard deviation of Inx). What proportion of battery lifetime values are at least 125 hours?

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The life of a cellphone battery has a lognormal distribution with μ = 4.5 and o= 0.4 (the mean
and standard deviation of Inx). What proportion of battery lifetime values are at least 125 hours?
Transcribed Image Text:The life of a cellphone battery has a lognormal distribution with μ = 4.5 and o= 0.4 (the mean and standard deviation of Inx). What proportion of battery lifetime values are at least 125 hours?
Expert Solution
Step 1: Introduce the given information

Given,

Mean, μ = 4.5

Standard deviation, σ = 0.4

And the distribution is lognormal distribution.

Let X be a random variable representing the battery lifetime values.

Using formula,

Z minus s c o r e equals fraction numerator ln X minus mu over denominator sigma end fraction

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