you can play around with Z Table stuff at
http://davidmlane.com/hyperstat/z_table.html
An automobile insurer has found that repair claims have a mean of $920 and a standard deviation of $870. Suppose that the next 100 claims can be regarded as a random sample from the long-run claims process. The probability that the average, x bar, of these 100 claims is larger than $1,000 is approximately
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