Suppose that the duration of a particular type of criminal trial is known to be normally distributed with a mean of 18 days and a standard deviation of 6 days. Let X be the number of days for a randomly selected trial. Round all answers to 4 decimal places where possible.

a. What is the distribution of X? X ~ N( , )

b. If one of the trials is randomly chosen, find the probability that it lasted at least 15 days.Answer=

c. If one of the trials is randomly chosen, find the probability that it lasted between 20 and 23 days. Answer=

d. 78% of all of these types of trials are completed within how many days? (Please enter a whole number)Answer=