SOLUTION: The scores on a college entrance examination are normally distributed with a mean of 550 and standard deviation of 100. For a sample of 30 students what is the probability that the

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Question 1152774: The scores on a college entrance examination are normally distributed with a mean of 550 and standard deviation of 100. For a sample of 30 students what is the probability that the sample has a mean of at least 600?
Answer by VFBundy(438) About Me  (Show Source):
You can put this solution on YOUR website!
z-score = %28600+-+mean%29%2F%28SD%2Fsqrt%28n%29%29 = %28600+-+550%29%2F%28100%2Fsqrt%2830%29%29 = 2.74

Look up 2.74 on a z-table. The result is 0.9969. This is the probability the mean is LESS THAN 600. So, the inverse of this is the probability the mean is MORE THAN 600. That result is 0.0031.