According to a survey by Topaz Enterprises, a travel auditing company, the average error by travel agents is $128. Suppose this figure was obtained from a random sample of 41 travel agents and the sample standard deviation is $21. What is the point estimate of the national average error for all travel agents? Compute 98% confidence interval for the national average error based on these sample results. Assume the travel agent errors are normally distributed in the population. How wide ia the interval? Interpret the interval.