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

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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) About Me  (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
z+=blue+%28xbar+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29
1.0364 (300/sqrt(64)) + 2400 = xbar