A bank official find that the length of time customers have to wait to be served by a teller are approximately normally distributed with a mean of 3 minutes and standard deviation of 1 minute. What is the probability that customers have to wait for longer than 2 minutes but less than 3.5 minutes? What is the probability that customers have to wait for 1 or less minute? What is the probability that customers have to wait for longer than 5 minutes