Consider the following practice problems: number 6, 7, and 8

6. A university has 1,000 computers available for students to use. Each computer has a 250-gigabyte hard drive. The university wants to estimate the space occupied on the hard drives. A random sample of 100 computers showed a mean of 115 gigabytes used with a standard deviation of 20 gigabytes. What is the probability that a sample mean is between 111 and 119 gigabytes? Z. A research firm conducted a survey to determine the mean amount people spend at a popular coffee shop during a week. They found the amounts spent per week followed a normal distribution, with a population standard deviation of $4. A sample of 49 customers revealed that the mean is $25. What is the 95% confidence interval estimate of u? 8. Sugar is packaged in 16-ounce bags. If 42 bags are sampled, with a mean of 15.95 ounces and a standard deviation of 0.4 ounces, what is the 99% confidence interval estimate of the population mean