Determine which type of confidence interval is appropriate (if any) in each situation. Type 1: estimate a population mean, population standard deviation is known Type 2: estimate a population mean,...

Determine which type of confidence interval is appropriate (if any) in each situation.

Type 1:estimate a population mean, population standard deviation is known

Type 2:estimate a population mean, population standard deviation is unknown

Type 3:estimate of a population proportion


If one of the above is appropriate, compute the confidence interval. Answers may be rounded to 3 decimal places. If none of the above are appropriate, state why. Clearly state all values you are using (for instance, the sample size, the z-score, etc. ).

• The American Heart Association is about to conduct an anti-smoking campaign and wants to know the fraction of Americans over 35 who smoke. Suppose a sample of 1421 Americans over 35 is drawn. Of these people, 412 smoke. Using the data, construct the 90% confidence interval for the population proportion of Americans over 35 who smoke.
  
  
  
  


• A fast food restaurant executive wishes to know how many fast food meals adults eat each week. They want to construct a 90% confidence interval for the mean and are assuming that the population standard deviation for the number of fast food meals consumed each week is 0.9. The study found that for a sample of 448 adults the mean number of fast food meals consumed per week is 7.4. Construct the desired confidence interval.
  
  
  
  


• A physicist examines 10 water samples for iron concentration. The mean iron concentration for the sample data is 0.711 cc/cubic meter with a sample standard deviation of 0.0816. Determine the 90% confidence interval for the population mean iron concentration. Assume the population is approximately normal.