Question 179188
BIG randomly selects 1000 Ultra batteries and finds that they have a mean lifetime of 921 hours. Suppose that this mean applies to the population of all Ultra batteries. Complete the following statements about the distribution of lifetimes of all Ultra batteries. 
Suppose that the distribution is bell-shaped. If approximatly 99.7% of the lifetime lie between 654 hours and 1188 hours, then the approximate value of the standard deviation for the distribution, according to the empirical rule is ___ 
6 sigma = (1188-654) = 534
sigma = 89
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Cheers,
Stan H.