A 
  beverage dispensing machine is calibrated so that the amount of beverage dispensed 
  is approximately normally distributed with a population standard deviation of 
  0.15 deciliters (dL). Compute a 95% confidence interval for the mean amount 
  of beverage dispensed by this machine based on a random sample of 36 drinks 
  dispensing an average of 2.25 dL. (State your answer as lower limit, upper limit).
  
 
  
Let's Do It! 10.17
 
  
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  How large of a sample would you need if you want the 
  width of the 95% confidence interval to be 0.04?
   
  
  
  
  
 
  Would a 90% confidence interval be wider or narrower 
  than the interval above.