A gas supplier maintains a team of engineers who are available to deal with leaks reported by customers. Most reported leaks can be dealt with quickly, but some require a long time. The time taken to deal with reported leaks is found to have a mean of 65 minutes and a standard deviation of 60 minutes. Assuming that the times may be modeled by a normal distribution, estimate the probability that it will take between 30 minutes and 60 minutes to deal with a reported leak.