The lengths of time bank customers must wait for a teller are normally distributed, with a mean of 3 minutes and a standard deviation of 1 minute.
1) What proportion of bank customers waits between 3 and 4 minutes
2) What percentage wait more than 3 minutes?
3) What proportion waits between 2.5 and 3.5 minutes?
4) What percentage wait less than 2 minutes?