1) when is sample mean normally distributed?

2) Some high schools teachers,teaching schools in outer islands demand an increase in meal allowances. According to a recent survey, the average cost of a meal is $6 in Ba. suppose this figure is based on a sample of 27 different restaurants with a sample standard deviation of $1. Construct a 95% confidence interval for the population mean cost of a fast food meal in Ba. Assume that the cost of fast food meals in Ba is normally distributed.

3) List 3 ways in which we can determine a good model fit?