Homework Help: math

Posted by King on Friday, May 25, 2012 at 12:55pm.

In a random sample of 1,000 exams, the average score was 500 points with a standard deviation of 80 points. Find the interval about the sample mean such that the probability is 0.90 that the mean number lies within the interval.

math - PsyDAG, Friday, May 25, 2012 at 3:05pm
90% = mean ą 1.645 SEm

SEm = SD/√n

I'll let you do the calculations.

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