can someone answer the following problems below and show work. The average diameter of sand dollars on a certain island is 4.00 centimeters with a...

Which of the above two problems (a) or (b) requires application of the Central Limit Theorem? Explain your reasoning.  

4. Assume that the mean diastolic blood pressure of normal adults is 80 millimeters of mercury (mm Hg) with a standard deviation of 4.8 mm Hg. Assume that the variable is normally distributed. If a sample of 30 adults is randomly selected, find the probability that the sample mean will be between 80 and 81.4 mm Hg.