The makers of a soft drink want to identify the average age of its consumers. A sample of 55 consumers was taken. The average age in the sample was 21 years with a standard deviation of 4 years.
a. Construct a 95% confidence interval for the true average age of the consumers.
b. Construct an 80% confidence interval for the true average age of the consumers.
c. Discuss why the 95% and 80% confidence intervals are different.