SOLUTION: The lifetimes of a certain brand of high intensity batteries are known to be normally distributed with a mean of 2,400 hours and a standard deviation of 300 hours. A random sample

Question 922357: The lifetimes of a certain brand of high intensity batteries are known to be normally distributed with a mean of 2,400 hours and a standard deviation of 300 hours. A random sample of 64 of these light bulbs is taken. The probability is 0.15 that the sample mean lifetime is more than how many hours?

Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
mean of 2,400 hours and a standard deviation of 300 hours
z = invNorm(.85) = 1.0364

1.0364 (300/sqrt(64)) + 2400 = xbar

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