In order to estimate the mean amount of time computer users spend on the interne

Question

In order to estimate the mean amount of time computer users spend on the internet each month, how many computer users must be surveyed in order to be 95% confident that your sample mean is within 13 minutes of the population mean? Assume that the standard deviation of the population of monthly time spent on the internet is 204 min. What is a major obstacle to getting a good estimate of the population mean? Use technology to find the estimated minimum required sample size.

The minimum sample size require is ___computer users

What is a major obstacle to getting a good estimate of the population mean?

A. It is difficult to precisely measure the amount of time spent on the internet, invalidating some data values.

B. The data does not provide information on what the computer users did while on the internet.

C.There may not be 946 computer users to survey.

D.There are no obstacles to getting a good esitmate of the population mean.

Explanation / Answer

a)

Note that      
      
n = z(alpha/2)^2 s^2 / E^2      
      
where      
      
alpha/2 = (1 - confidence level)/2 =    0.025  
      
Using a table/technology,      
      
z(alpha/2) =    1.959963985  
      
Also,      
      
s = sample standard deviation =    204  
E = margin of error =    13  
      
Thus,      
      
n =    945.953552  
      
Rounding up,      
      
n =    946   [ANSWER]

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b)

A. It is difficult to precisely measure the amount of time spent on the internet, invalidating some data values. [ANSWER, A]

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