A particular automobile costs an average of $21,755 in the Pacific Northwest. The standard deviation of prices is $650. Suppose a random sample of 40 dealerships in Washington and Oregon is taken and their managers are asked what they charge for this automobile. What is the probability of getting a sample average cost of less than $21,500? Assume that only 120 dealerships in the entire Pacific Northwest sell this automobile.

(Round z values to 2 decimal places, e.g. 0.75. Round all intermediate calculation and answers to 4 decimal places, e.g. 0.7571.)

Appendix A Statistical Tables

p=

enter probability rounded to 4 decimal places