The basal diameter of sea anemone is an indicator of its age, and in certain population of anemones, the distribution of basal diameters is approximately normal with a mean of 4.1 cm and a standard deviation of 1.3 cm. Suppose you randomly select 4 anemones from this population.
a. What is the probability that all 4 anemones have a basal diameter between 3.5 and 4.5 cm?
b. What is the probability that the mean basal diameter of the 4 anemones is between 3.5 and 4.5 cm?