A website has determined that the length of time that users spend on its site is normally distributed with a mean of 5.83 minutes and a standard deviation of 1.89 minutes.
Find: (a) the probability that a user will stay on the site for more than 7 minutes.
(b) the probability that a user will stay on the site between 2 and 5 minutes.
(c) the 41st percentile for the length of time spent on the site (a time such that 41% of users stay less than that time).
(d ) the probability that a random sample of 30 users has a mean of more than 5 minutes on the site.