An accountant of wallie's the pizza franchise claims that its stores generate average weekly revenues of at least $7,000 per store. a potential buyer who is considering purchasing a wallie's pizza franchise is doubtful about this claim, and believes instead that the average weekly revenue might be less than $7,000. with some effort, he obtains revenues from 20 wallie's stores across the country by interviewing their managers/employees and finds that the average revenue is $6400. historical tax filings by wallie's indicate that the standard deviation of revenues has been about $1042. store revenues are assumed to be normally distribute d. what is the calculated value of the statistic to test the potential buyer's belief at the 1% level of significance?