The monthly closing stock prices (rounded to the nearest dollar) for Panera Bread Co. for the first six months of 2010 are reported in the following table. Use Table 2.

Months	Closing Stock Price
January 2010	$71
February 2010	73
March 2010	76
April 2010	78
May 2010	81
June 2010	75

SOURCE: http://finance.yahoo.com.

a.	Calculate the sample mean and the sample standard deviation. (Round intermediate calculations to 4 decimal places. Round "Sample mean" and "Sample standard deviation" to 2 decimal places.)

Sample mean
Sample standard deviation

b.	Compute the 90% confidence interval for the mean stock price of Panera Bread Co., assuming that the stock price is normally distributed. (Round "t" value to 3 decimal places, and final answers to 2 decimal places.)

Confidence interval

to

c.

What happens to the margin of error if a higher confidence level is used for the interval estimate?

	The margin of error increases as the confidence level increases.
	The margin of error decreases as the confidence level increases.