A university has 1000 computers available for students to use. Each computer has an 850-gigabyte hard drive. The university wants to estimate the space occupied on the hard drives. A random sample of 51 computers showed a mean of 623 gigabytes used with a standard deviation of 76 gigabytes. a. The University was told that computers should have at least 25% of the hard drive space free - more than 637 gigabytes. What is the likelihood that they have, on average, more than 637 GB of space free?