Question

In: Statistics and Probability

A battery company claims that their batteries last on average 60 hours. The standard deviation of...

A battery company claims that their batteries last on average 60 hours. The standard deviation of the battery life is 4 hours. Assuming that their claim is true, what would be the lowest 5% of values we would get if we were to sample 100 batteries and find their mean life length?

Please show me how to do it, thank you!

Solutions

Expert Solution

Given that,

mean = = 60

standard deviation = = 4

n = 100

= 60

= / n = 4 /100=0.4

Using standard normal table,

P(Z < z) = 5%

= P(Z < z) = 0.05  

z =-1.65 Using standard normal table,

Using z-score formula  

= z * +   

=-1.65 *0.4+60

= 59.34


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