An oceanographer is studying the relationship between the slope of beaches and the mean grain size

(D, mm) of the sand. For slopes of about 6°, the expected mean is 0.45 mm, with a variance of 0.012 mm2. What is the confidence interval on the mean if the oceanographer collects the following mean grain size at six beaches: {0.43, 0.38, 0.35, 0.46, 0.32, 0.30} mm? Using the confidence interval, discuss whether or not these six beaches are representative of the population.