Question 184261
An ice cream store manager thinks that the average bill paid by his customers is $10. To test his hypothesis, the next 20 tabs are tallied. All of them are over $10. Therefore, he can conclude immediately that the average bill paid by all of his customers
a. exceeds $10. 
b. may be less than, equal to, or greater than $10.
c. is less than $10.
d. equals $10.
*I was thinking (a.), is this the correct answer?
If not can you please explain why, and which one would be the best answer? 
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"a" appears to be the reasonable answer but it is not the statistical
answer. "b" is the statistical answer.  The fact that 20 or even 2000
bills are ore than $10 does not prove anything.
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Cheers,
Stan H.