There are 572 full-service restaurants in Vermont. The mean number of seats per restaurant is 65.7. [Source: Data based on the 2002 Economic Census from U. S. Census Bureau.] Suppose that the true population mean mu = 65.7 and standard deviation sigma = 20.8 are unknown to the Vermont tourism board. They select a simple random sample of 55 full-service restaurants located within the state to estimate mu. The mean number of seats per restaurant in the sample is M = 69.9, with a sample standard deviation of s = 19.1. The standard deviation of the distribution of sample means (that is, the standard error, sigmaM) is . (Note: Although mu and sigma are unknown to the Vermont tourism board, they are known to you for the purposes of calculating these answers.)