The monthly closing stock prices (round to the nearest dollar) for Panera Bread
ID: 3364994 • Letter: T
Question
The monthly closing stock prices (round to the nearest dollar) for Panera Bread Co. for the first six months of 2010 are reported in the following table:
Months Closing Stock Price
January 2010 $255
February 2010 254
March 2010 259
April 2010 258
May 2010 257
June 2010 251
a.Calculte the sampe mean and the sample deviation. (round intermediaite calcualtions to 4 decimal places and sample mean and sample standard deviation to 2 decimal places,)
b. Compute the 90% confidence interval for the mean stock price of Panera Bread Co. assuming the stock price is normally distributed. (round t value to 3 decimal places and final answer to 2 decimal places.)
c. What happens to the margin of error if a higher confidence level is used for the interval estimator?
Explanation / Answer
a )
Sample mean = 255.67
Sampel sd = 2.94
b)
Standard error of the mean = SEM = S/N = 1.2
t(, N-1) = 2.015
Confidence interval = m +/- (t(, N-1)*SEM)
Mean = 255.67
Lower bound: 253.25
Upper bound: 258.09
c)
As theconfidence level increases, the margin of errorincreases.