The standard deviation of the 2011 gross sales of all corporations is known to be $139.50 million.

Question:

The standard deviation of the 2011 gross sales of all corporations is known to be $139.50 million. Let x̅ be the mean of the 2011 gross sales of a sample of corporations. What sample size will produce the standard deviation of equal to $15.50 million? Assume n/N < .05.