SOLUTION: Suppose a random sample of size 36 is drawn from a population with a mean 278. If with probability 86% the sample mean is less than 280, what is the population standard deviation?

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Question 924516: Suppose a random sample of size 36 is drawn from a population with a mean 278. If with probability 86% the sample mean is less than 280, what is the population standard deviation?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
mean 278
z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29
z = invNorm(.86) = (280-278)/(sd/√36)
1.0803 = 2/(sd/6)
(sd/6)(1.0803) = 3
sd = 18/1.0803 = 16.6620 rounded (use the number of decimal points as directed)