1.      

   Use the confidence level and sample data to find the margin of
   error E. Round your answer to the same number of decimal places as
   the sample mean unless otherwise noted.  College
   students’ annual earnings: 99% confidence; n = 76,

   Answer         
     

   		$196
   		$891
   		$233
   		$258

           

                   

     

             

1.      

   Use the confidence
   level and sample data to find a confidence interval for estimating
   the population mu.  Round your answer to the same number
   of decimal places as the sample mean. A random sample of 105 light
   bulbs had a mean life of 441 hours with a standard deviation of 40
   hours.  Construct a 90% confidence interval for the mean
   life, mu, of all light bulbs of this type.

   Answer         
     

   		433 hr < mu <  449 hr
   		435 hr < mu <  447 hr
   		431 hr < mu <  451 hr
   		432 hr < mu <  450 hr

           

                   

     

             

1.      

   Use the given
   information to find the minimum sample size required to estimate an
   unknown population mean mu. How many women must be randomly
   selected to estimate the mean weight of women in one age
   group.  We want 90% confidence that the sample mean is
   within  3.7 lb of the population mean, and the population
   standard deviation is known to be  28 lb.

   Answer         
     

   		221
   		156
   		153
   		155

           

                   

     

             

1.      

   Assume that a sample
   is used to estimate a population mean mu. Use the given confidence
   level and sample data to find the margin of error. Assume that the
   sample is a simple random sample and the population has a normal
   distribution. Round your answer to one more decimal place than the
   sample standard deviation.     95%
   confidence; n = 21; x-bar = 0.16; s = 0.16

   Answer         
     

   		0.085
   		0.068
   		0.063
   		0.073

           

                   

     

             

1.      

   Use the given degree
   of confidence and sample data to construct a confidence interval
   for the population mean mu.  Assume that the population
   has a normal distribution. Thirty randomly selected students took
   the calculus final.   If the sample mean was 83 and the
   standard deviation was 13.5, construct a 99% confidence interval
   for the mean score of all students.

   Answer         
     

   		76.21 < mu < 89.79
   		76.23 < mu < 89.77
   		76.93 < mu < 89.07
   		78.81 < mu < 87.19

           

                   

     

             

Solve the problem.  Find the critical value   corresponding to
a sample size of 24 and a confidence level of 95 percent.